Question

If you were to use the substitution method to solve the following system, choose the new equation after the expression equivalent to x from the first equation is substituted into the second equation. x + 4y = −9 2x + 5y = −6

Answer 1

Hence, the required equation is:

-18-3y= -6

Explanation:

We are asked to solve a system of equation using the substitution method i.e. we need to apply:

choose the new equation after the expression equivalent to x from the first equation is substituted into the second equation

The system of equations is given as:

x + 4y = −9 -------(1)

2x + 5y = −6------(2)

now we find the value of x from equation (1) in terms of y:

x= -9-4y.

and put this value of x in equation (2) to obtain:

2(-9-4y)+5y= -6

-18-8y+5y= -6

-18-3y= -6

Answer 2

x + 4y = -9 . . . (1)
2x + 5y = -6 . . . (2)

From (1): x = -9 - 4y . . . (3)

Substituting (3) into (2) gives, 2(-9 - 4y) + 5y = -6
-18 - 8y + 5y = -6
Required equation is -18 - 3y = -6