Question

What is the best first step for solving the given system using substitution while avoiding fractions?

2x+6y=7
6x+18y=24

a. Solve for x in the first equation.
b. Solve for y in the first equation.
c. Solve for x in the second equation.
d. Solve for y in the second equation.

Answer 1

solve with subsitution avoiding fractions

2x+6y=7
6x+18y=24

if we solve for x in first, we get x=-3y+7/2, has fractions so no
if we solve for y in first, we get y=-x/3+7/6, has fractions so no
if we solve for x in the 2nd, we get x=-3y+4, no fractions so yay
if we solve for y in the 2nd, we get y=-x/3+4/3, has fractions so no


answer is C

Answer 2

Well, it says to avoid fractions. So I did the math:

Solving for x in the first equation get you:
`x= (7)/(2)-3y`

Solving for y in the first equation gets you:
`y= (7)/(6) - (2)/(6)x`

Solving for x in the second equation gets you:
`x=4-3y`

Solving for y in the second equation gets you:
`y= (24)/(18) - (6)/(18)x`

If you look you can see the only option that does not give you fractions is if you solve for x in the second equation. So your answer is c! I hope this helps! =)