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Elan Coil [88]
3 years ago
9

If 7x - 4y = 23 and x + y = 8, what is the value of x?

Mathematics
2 answers:
Margaret [11]3 years ago
8 0

Answer:

x=5

Step-by-step explanation:

7x - 4y = 23 and x + y = 8

Multiply the second equation by 4

4x + 4y = 32

Add this to the first equation

7x - 4y = 23

4x + 4y = 32

------------------------

11x    = 55

Divide each side by 11

11x/11 = 55/11

x = 5

QveST [7]3 years ago
5 0

Answer:

\huge\boxed{x=5}

Step-by-step explanation:

\left\{\begin{array}{ccc}7x-4y=23\\x+y=8&|\text{subtract}\ x\ \text{from both sides}\end{array}\right\\\left\{\begin{array}{ccc}7x-4y=23&(1)\\y=8-x&(2)\end{array}\right\\\\\text{substitute (2) to (1):}\\\\7x-4(8-x)=23\qquad|\text{use the distributive property}\\\\7x+(-4)(8)+(-4)(-x)=23\\\\7x-32+4x=23\qquad|\text{combine like terms}\\\\(7x+4x)-32=23\qquad|\text{add 32 to both sides}\\\\11x-32+32=23+32\\\\11x=55\qquad|\text{divide both sides by 11}\\\\\dfrac{11x}{11}=\dfrac{55}{11}\\\\x=5

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Answer:

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Step-by-step explanation:

To find out if 84 is a solution or not, we plug in the value and simplify.

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Therefore, 84 is a solution.

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Assume that different groups of couples use a particular method of gender selection and each couple gives birth to one baby. Thi
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Complete question:

Assume that different groups of couples use a particular method of gender selection and each couple gives birth to one baby this mention is designed to increase the likelihood that each baby will be a girl, but assume that the method has no effect so the probability of a girl is 0.5. Assume that the group consists of 36 couples.

A) Find the mean and standard deviation for the number of girls in groups of 36 births.

B) Use the range rule of thumb to find the values separating results that are significantly low and significantly high.

C) Is the result of 33 girls significantly high? A result of 33 girls would suggest the method is effective or is not effective?

Answer:

a) mean = 18

Standard deviation =3

b) low range = 12

High range = 24

c) The result of 33 girls is significantly high. Yes, the method is effective.

Step-by-step explanation:

Given:

p = 0.5

n = 36

a) The mean is the product of n and p

Mean u = np

u = 36 * 0.5 = 18

The standard deviation is the square root of the product of n and p&q.

S.d ó = \sqrt{npq}

= \sqrt{np(1-p)}

= \sqrt{36(0.5)(1-0.5)} = \sqrt{9} = 3

b) To find the range rule of thumb:

• For low range

Low range = u - 2ó

= 18 - (2 * 3)

= 12

• High range

= u + 2ó

= 18 + (2*3)

= 24

c) The result is significantly high, because 33 is greater than 24 girls.

A result of 33 girls would prove the method as effective.

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3 years ago
(Please help) What is the rate of change of y with respect to x?
dolphi86 [110]

answer will be 2÷18=9

and the answer is 9

please mark this answer as brainlist

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