2. (a) Use a prove by contradiction to show that if a and b are nonzero integers such that a divides b and a + b is odd, then a is odd. (b) Prove that if n is a positive integer, then n² does not equal 2(mod 4).
Answers
a. Assume a is even, so a = 2k for some integer k. Now let a and b be integers such that a divides b and a + b is odd.
Since a divides b, b = an for integer n, and in turn b = 2nk, which means b is even and hence a + b is also even. But this contradicts our initial assumption, so a must be odd.
b. Let n be even, so that n = 2k for some integer k. Then
n² = (2k)² = 4k²
so that n² ≡ 0 (mod 4).
Now let n be odd, so n = 2k + 1 for integer k. Then
n² = (2k + 1)² = 4k² + 4k + 1
so that n² ≡ 1 (mod 4).
Therefore n² is never congruent to 2 (mod 4).
Related Questions
Solve the Quadratic
Solve for x. Write in simplified radical form.
2x^2 + 3x – 20 = 0
Solution 1:
Solution 2:
Answers
~quadratic equation
======================
2x² + 3x - 20 = 0
= a + b = 3
= ab = 2(-20) = -40
= a = -5
= b = 8
= (2x² - 5x) + (8x - 20)
= x(2x - 5) + 4(2x - 5)
= (2x - 5) (x + 4)
= Solution 1 : x = 5/2 ✔️
Solution 2 : x = -4 ✔️
~ nice to help you ^^
[tex]2x^2 +3x -20 =0\\\\\\\implies x = \dfrac{-3 \pm \sqrt{(-3)^2 - 4 \cdot 2 \cdot (-20)}}{2 \cdot 2}\\\\\\\implies x = \dfrac{-3 \pm \sqrt{169}}{4}\\\\\\\implies x = \dfrac{-3\pm 13} 4 \\\\\\\text{Hence} \\\\x = \dfrac{-3+ 13}{4} = \dfrac{10} 4 = \dfrac{5}2\\\\\text{Or}\\\\x= \dfrac{-3-13}4 = -\dfrac{16}4 =-4[/tex]
An unopened bag of gummy bears weighs 2 1/3 ounces. Drayven has 3/4 of a bag of gummy bears and Akila has 2/3 of a bag. Who has more? If they put their bags together, would they have more than one bag? Explain your answer.
Answers
Answer:
Drayven has more
Step-by-step explanation:
If you look at the fractions through a drawing you would see that my claim is correct.
How many solutions for
55l=50l+5
Answers
Answer:
Zero
Step-by-step explanation:
The question is impossible to answer. 501+5 does not equal 551, 501+5 equals 506.
2. If (2, 3) is an ordered pair of the
function F(x), which of the following
must be an ordered pair of the inverse
of F(x)?
Answer Choices:
(3, 2)
(-2,-3)
(2,3)
(-3,-2)
Answers
Answer:
Inverse: (3, 2)
Step-by-step explanation:
Given the point, (2, 3), as an ordered pair of the function, f(x):
Since we know that for any functions, there is a one-to-one correspondence between each domain and range values. Conversely, each range value also corresponds to one domain value.
The inverse of a function, [tex]f^{-1}(x)[/tex], also has a one-to-one correspondence. Simply put, we are essentially switching the x and y values to determine the inverse of a function.
Therefore, given the ordered pair from f(x) = (2, 3), then the corresponding coordinates in the inverse function, [tex]f^{-1}(x)[/tex], must be (3, 2).
At the store the ratio of books sold to movies sold was 4:5.For every_books sold there were _ movies sold.
Answers
Answer:
At the store the ratio of books sold to movies sold was 4:5.For every 4 books sold there were 5 movies sold.
Step-by-step explanation:
Suppose you are reviewing your cell phone bill on Friday and you notice you go over your data limit 49% of the time. You
review the weather forecast for tomorrow that says there is a 11% chance of rain. Assuming rain and going over in data are
independent events, what is the probability that it rains and you go over in data tomorrow? Give your answer as an exact
fraction and reduce the fraction as much as possible.
Answers
Probability that it rains and you go over in data tomorrow = 0.0539
Percentage of time it takes to go over your data limit = 49%
Probability that you go over your data limit, P(data) = 49/100
P(data) = 0.49
The chance that it rains tomorrow = 11%
Probability that it rains tomorrow, P(rain) = 11/100
Probability that it rains tomorrow, P(rain) = 0.11
Probability that it rains and you go over your data tomorrow = P(rain) x P(data)
Probability that it rains and you go over in data tomorrow = 0.11 x 0.49
Probability that it rains and you go over in data tomorrow = 0.0539
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dont sound so smart doing it she will know
Answers
Jeremy is incorrect because a negative plus a negative will always be a negative.
Natasha earns $425 a week. How many weeks does it take before she has
earned more than $12, 000
Answers
Answer:
29
Step-by-step explanation:
12000/425
passes through (2,-3) with a slope of -9/2
Answers
Answer:
y = — 9/2x + 6
Step-by-step explanation:
m= —9/2
y — y1 = m (x — x1)
y + 3 = —9/2 (x — 2)
y = — 9/2x + 6
Felicia bought 20.8 gallons of gasoline. There are approximately 3.8 liters in 1 gallon.
Answers
Answer:
79.04 liters
Step-by-step explanation:
20.8 x 3.8 = 79.04
Express 24 minutes as a fraction of 2'/2 hours.
Answers
Step-by-step explanation:
1hr = 60
½ hr = 30
60 + 30 = 90
Find x using the pictures below please. Will mark branliest for first reply.
Answers
Step-by-step explanation:
a) We are going g to use the definition of tangent to find x:
[tex]\tan{18°} = \dfrac{opp}{adj} = \dfrac{15}{x}[/tex]
[tex]\Rightarrow x = \dfrac{15}{\tan{18°}} = 46.2[/tex]
b) To solve this problem, we are going to use the definition of cosine:
[tex]\cos{70°} = \dfrac{adj}{hyp} = \dfrac{x}{46}[/tex]
[tex]\Rightarrow x = 46\cos{70°} = 15.7[/tex]
What would you do if you found out that you wrote a cheque of $78 but it was recorded as $98 in check register?
Answers
Answer:
I will cryy because I only want to write 78 why it recorded as 98
An eight-sided dice numbered from 1 to 8 is rolled 80 times to determine whether it is fair, a If the dice is fair, how many of each number would you expect to get?
Answers
Answer:
10 times for each number
Step-by-step explanation:
:)
Answer:
10
Step-by-step explanation:
if the dice is fair, the sides will land one time every 8, so if its rolled 80 time, and it was equal 10 would be your answer.
help me please !!!!!!
KS3 YEAR 8 maths!
super confused ♀️♀️
Answers
Answer:
9:29pm
Step-by-step explanation:
How do I do this math !
Answers
Answer:
The equation of a straight line is always
[tex]y=mx+b[/tex]
The constant m always refers to the slope, and the constant b always refers to the y-intercept.
Simply substitute the numbers in:
[tex]y=-\frac{1}{2}x+3[/tex]
There's your equation!
Write an algebraic expression for the verbal expression: "7 times the sum of a squared and b minus 4 times the sum of a squared and b".
Answers
an oven has a maximum temperature of 220°c.what will it be in 2 days time
Answers
Answer:
Well I assume 220ºC.
Step-by-step explanation:
That is the MAXIMUM temperature of the oven
A waiter carried 6 baskets with 5 dinner rolls in each
basket. How many dinner rolls did he carry? Show
your work.
Answers
Answer:
30 dinner rolls
Step-by-step explanation:
There are 5 dinner rolls per basket and there are 6 baskets
So there are 6 groups of 5:
5 + 5 + 5 + 5 + 5 + 5
In other words, multiply 5 and 6
5 dinner rolls x 6 = 30 dinner rolls
Each basket has five rolls so you have to do 5+5+5+5+5+5 which equals 30
Which number should be multiplied by 45 so that it will have 3 nct prime factors?
Answers
Answer:
2
Step-by-step explanation:
These points are linear.
Find the slope.
M=?
Answers
Answer:
Step-by-step explanation:
(5, 0) (6, 8)
(8 - 0)/(6 - 5) = 8/1 = 8
Question
Given that the market basket for gardening was $\$131.17$ last year and $\$131.96$ this year, what was the inflation rate?
(Round your answer to the nearest hundredth of a percent.)
Answers
Answer:
0.006%
Step-by-step explanation:
minused old price from the new one and then divided the answer by the old price
50° x
how to find value of unknown angle
Answers
Answer:
a) 50
b) 86
c) x = 130 y = 50
Step-by-step explanation:
Opposite angles that share the same lines are always the same.
Write the equation of the line in slope intercept form
Slope =−1/5 Y-Intercept =−3
Answers
Answer:
y = mx + c ......( general form)
y = -1/5X - 3
The percent of Ivy Tech students receiving financial aid in 2018 was 82%, this was a 9.8% relative increase from 2017. What would the percent of students receiving aid in 2017 have been?
Answers
Question 1 of 10
f (2) = y + 10. Find the inverse of f(x).
O A f-'(x) = (x + 10)
O B. f-1(x) = 73 + 10
O C. f-1(x) = (x – 10)3
O D. f-'(x) = x3 – 10
Answers
Option D
step by step explanation:
[tex] \sf f(x) = \sqrt[3]{x + 10} \\ \sf y = \sqrt[3]{x + 10} \\ \sf y = \sqrt[3]{y + 10} \\ \sf y = {x}^{3} - 10 \\ \sf {f}^{ - 1} (x) = {x}^{3} - 10[/tex]
The inverse of the given function is represented as f' ( x ) = x³ - 10
What is Function Rule?A function is a mathematical object that takes an input (or several inputs) and produces an output. The rule of a function describes how the input is transformed to produce the output. It can be written using mathematical notation, words, or a combination of both.
Functions are used in many areas of mathematics, science, engineering, and other fields to model relationships between variables, make predictions, and solve problems.
Given data ,
Let the function be represented as A
Now , the value of A is
Now , the function is depicted as f ( x ) = ∛( x + 10 )
Simplifying results in
The function's inverse is obtained by swapping the x and y variables.
So ,
y = ∛( x + 10 )
x = ∛( y + 10 )
On solving for y , we get
y = x³ - 10
And , the inverse is f' ( x ) = x³ - 10
The function is therefore f' (x) = x³ - 10.
Go here to read more about the function rule.
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Crafts Unlimited sells ribbon by the foot. Serena needs ribbon
for an art project. The cost of the ribbon is 5 feet for $3.00.
Feet of Ribbon 1 5 10 15
Cost (in dollars) $3.00
a. Complete this ratio chart based on the information provided.
b. How many feet of ribbon can Serena buy for $12.00?
c. If Serena needs 17 feet of ribbon, how much will she pay?
How do you know?
Answers
The completed ratio chart is provided below:
Feet of Ribbon 1 5 10 15
Cost $0.60 $3 $6 $9
The amount Serena would get if she has $12 is 20 yards.
The amount Serena would pay if she wants 17 feet of the ribbon is $10.20.
The first step is to determine the unit cost of a ribbon.
Unit cost of a ribbon = $3 / 5 = $0.60
The cost of 10 feet of the ribbon = $0.60 x 10 = $6
The cost of 15 feet of the ribbon = $0.60 x 15 = $9
The feet of ribbon Serena can buy if she has $12 = $12 / $0.60 = 20 yards.
The cost of 17 feet of the ribbon = $0.60 x 17 = $10.20
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There are m marbles in a bag. Write an expression for the number of marbles in the bag when 4 marbles are taken away
Answers
Answer:
m-4
Step-by-step explanation:
4 marbles taken away = -4 marbles
Need all of these answered please
Answers
alternate entireror angles are congurent by this rule you can find your answer by solving the equation
What is the temperature change between the greatest value and the least value?
-25°F, 5°F, 60°F, -45°F, -10°F, 90°F
WILL BR MARKED BEST
Answers
Highest- 90 degrees
Lowest- -45 degrees
-45 to 0 = 45 units
0 to 90 = 90 units
45+90 units = 130
ANSWER 130