Question

For the following system, use the second equation to make a substitution for x in the first equation. x + 2y = 7 x + 5 = 3y What is the resulting equation? 3y - 5 - 2y = 7 3y + 5 + 2y = 7 3y - 5 + 2y = 7

Answer 1

3y - 5 + 2y = 7

Explanation:

Subtracting 5 from the second equation gives ...

x = 3y -5

Using the expression on the right for x in the first equation gives ...

x + 2y = 7 . . . . . . . . first equation

(3y -5) +2y = 7 . . . . with expression substituted for x

3y - 5 + 2y = 7 . . . . with parentheses removed