Question

Use the substitution method to solve the system of equations. choose the correct ordered pair.

y= -2x+11
y= -3x+21

A. (-12,-8)
B.(11,-12)
C. (8,-13)
D. (10,-9)

Answer 1

D

Explanation:

Since both equations express y in terms of x, equate the right sides

- 2x + 11 = - 3x + 21 ( add 3x to both sides )

x + 11 = 21 ( subtract 11 from both sides )

x = 10

substitute x = 10 into either of the 2 equations for y

y = - 2x + 11 = - 20 + 11 = - 9

solution is (10, - 9) → D

Answer 2

The correct option is D. (10,-9)

Explanation:

Consider the provide equation.

`y= -2x+11\\y= -3x+21`

Equate both the equation as shown.

`-3x+21=-2x+11`

Add 2x both the sides.

`-3x+2x+21=-2x+2x+11`

`-x+21=11`

Subtract 21 from both sides.

`-x+21-21=11-21`

`-x=-10`

`x=10`

Now substitute the value of x in
`y= -2x+11`

`y= -2(10)+11`

`y= -20+11`

`y= -9`

Hence the value of x and y is 10 and -9 respectively.

Thus, the correct option is D. (10,-9)