Question

Use the substitution methods to solve the system of equations. Choose the correct ordered pair. y=7x+8 y=x+20

a. (3,29)
b. (2,8)
c. (7,8)
d. (2,22)

Answer 1

d

Explanation:

Solution by substitution method

y=7x+8

∴y-7x=8

and y=x+20

∴y-x=20

Suppose,

-7x+y=8→(1)

and -x+y=20→(2)

Taking equation (1), we have

-7x+y=8

⇒y=7x+8→(3)

Putting y=7x+8 in equation (2), we get

-x + 7x + 8 = 20

6x = 20-8

6x = 12

x= 12 / 6

x = 2

substitute for x in equation (3)

y = 7(x) + 8

y = 7(2) + 8

y = 22