Question

question 25 of 25
which of these shows the result of using the first equation to substitute for y in the second equation, then combining like terms?

y = 3x
3x + 2y = 18

a. 3y = 18
b. 6x = 18
c. 3x = 18
d. 9x = 18

Explanation:

Step1: Substitute \( y = 3x \) into the second equation

The second equation is \( 3x + 2y = 18 \). Replace \( y \) with \( 3x \), we get \( 3x + 2(3x) = 18 \).

Step2: Simplify the left - hand side

First, calculate \( 2(3x)=6x \). Then, combine like terms \( 3x+6x \). According to the rule of combining like terms (adding the coefficients of the same variable), \( 3x + 6x=(3 + 6)x=9x \). So the equation becomes \( 9x = 18 \).

Answer:

D. \( 9x = 18 \)