Question

Use substitution to solve the system of equations.

y = 2x + 16
2x – 7y = –64

A) (–4, 8)

B) (–1, 11)

C) (8, –4)

D) (–7, –11)

Answer 1

Explanation:

y = 2x + 16............equation 1

2x - 7y = -64..........equation 2

Now putting y = 2x +16 in equation 2

2x - 7(2x + 16) = -64

2x - 14x - 112 = -64

-12x = -64+112

-12x = 48

Therefore x = -4

Now putting x = -4 in equation 1

y = 2*(-4) +16

= -8 +16

= 8

Answer 2

A) (–4, 8)

Explanation:

to solve this system of equation

we will say let

y = 2x + 16 ............................. equation 1

2x – 7y = –64............................ equation 2

substitute equation 1 into equation 2

2x – 7y = –64............................ equation 2

2x - 7( 2x + 16) = -64

2x - 14x -112 = -64

combine the like terms

2x - 14x = -64 +112

-12x = 48

divide both sides by the coefficient of x

-12x/-12 = 48/-12

x = -4

put the value of x = -4 into equation 1

y = 2x + 16 ............................. equation 1

y = 2(-4) + 16

y = -8 + 16

y = 8

therefore the value of x and y is -4 and 8 respectively