Question

Use substitution to solve the system of equations. 18 = x – 3y 2x + 19 = –5y A. (3, –5) B. (6, 10) C. (–11, 9) D. infinitely many solutions

Answer 1

(3, –5)

Explanation:

Answer 2

A. (3, -5)

Explanation:

Use the first equation to find an expression for x. (Add 3y.)

x = 18 + 3y

Now, use this where x is in the second equation.

2(18 +3y) +19 = -5y

55 +6y = -5y . . . . . . . eliminate parentheses

55 +11y = 0 . . . . . . . . .add 5y

5 +y = 0 . . . . . . . . . . .divide by the coefficient of y

y = -5 . . . . . . . . . . . . . add -5; corresponds to answer choice A

Using the expression for x, we can find its value:

x = 18 +3(-5) = 3

The solution is (x, y) = (3, -5). . . . . . matches choice A