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4 years ago

PLEEEASE HELLLLP!!!!!!! If x+7=2y and y=2x−1, what is the value of y?

Mathematics

1 answer:

viktelen [127]4 years ago

6 0

Answer:

Step-by-step explanation:

We can add 1 to both sides of the second equation and divide by 2 to get

x = (y-1)/2

We can then substitute x in the first equation to get

(y-1)/2 + 7 = 2y

Multiply by 2

y-1 + 14 = 2y

Subtract y and combine like terms

y = 13

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Is the square root of 23 rational or irrational

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3 years ago

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Your classroom received 150 books. You are placing them in bins. Each bin holds 20 books. How many bins do you need? Remainder:

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3 years ago

I need help what’s is the value of x!!

Shalnov [3]

Answer:

y= -1 or y equals negative 1

Step-by-step explanation:

-4(y) (-4)(-2) = 12

-4y + 8 = 12

-4y = 4

divide 4 by both sides

-y = 1

y= -1

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3 years ago

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Drag the tiles to the correct boxes to complete the pairs. Not all tiles will be used. Match the linear equations with their x-

jolli1 [7]

Answer:

Part 1) $x-2y=2$ ----> (2,0) and (0,-1)

Part 2) $-3x+3y=7$ ----> (-7/3,0) and (0,7/3)

Part 3) $7x-y=21$ ----> (3,0) and (0,-21)

Part 4) $3x-5y=-20$ ----> (-20/3,0) and (0,4)

Step-by-step explanation:

we know that

The y-intercept is the value of y when the value of x is equal to zero

The x-intercept is the value of x when the value of y is equal to zero

Part 1) we have

$x-2y=2$

1) Find the x-intercept

For y=0

$x-2(0)=2\\x=2$

the x-intercept is (2,0)

2) Find the y-intercept

For x=0

$0-2y=2\\y=-1$

the y-intercept is (0,-1)

Part 2) we have

$-3x+3y=7$

1) Find the x-intercept

For y=0

$-3x+3(0)=7\\x=-\frac{7}{3}$

the x-intercept is (-7/3,0)

2) Find the y-intercept

For x=0

$-3(0)+3y=7\\y=\frac{7}{3}$

the y-intercept is (0,7/3)

Part 3) we have

$7x-y=21$

1) Find the x-intercept

For y=0

$7x-(0)=21\\x=3$

the x-intercept is (3,0)

2) Find the y-intercept

For x=0

$7(0)-y=21\\y=-21$

the y-intercept is (0,-21)

Part 4) we have

$3x-5y=-20$

1) Find the x-intercept

For y=0

$3x-5(0)=-20\\x=-\frac{20}{3}$

the x-intercept is (-20/3,0)

2) Find the y-intercept

For x=0

$3(0)-5y=-20\\y=4$

the y-intercept is (0,4)

8 0

4 years ago

A new medical test has been designed to detect the presence of the mysterious Brainlesserian disease. Among those who have the d

astra-53 [7]

Answer:

Step-by-step explanation:

The persons who have diseases = 19%

The persons who do not have diseases = 81%

Probability for the test showing positive = Prob of actual disease and shows positive + Prob of no disease but test shows wrong

= $0.7*0.19+0.04*0.81\\=0.133+0.0324\\=0.1654$

Prob that the person actually has the disease given that the test administered to an individual is positive= $\frac{0.133}{0.1654} \\=0.0804$

30) A B C total

2x 7x x 10x

P(A) = 0.2, P(B) = 0.7, P(C) = 0.1

Let D be the event that the product is defective

P(D/A) = 0.032, P(D/B) = 0.034 and P(D/C) = 0.056

Required probability =P(C/D)

= $\frac{P(D/C) P(C)}{P(D/A) P(a)+P(D/B) P(B)+P(D/C) P(C)}$

by using Bayes theorem for conditional probability

= $\frac{0.1*0.056}{0.2*0.032+0.7*0.034+0.1*0.056} \\=\frac{0.0056}{0.0064+0.0238+0.0056} \\\\=0.156425$

32) 7 digit phone numbers with repitition including 0 will be

= $10^7$

Numbers which have atleast one 7 = total number - numbers which do not have a single 7

= $10^7 -9^7$

the probability that a 7-digit phone number contains at least one 7

= $\frac{10^7-9^7}{10^7}$

3 0

3 years ago