Question

Simplify -3xy 3 + 7xy 3 + (-xy 3) + (-3xy 3).



0

xy3

3xy3

-xy3

Answer 1

We are given:
x+2y=0
3x-y=3
use second equation and solve for y
add y to both sides of =, then subtract
3 from both sides of =
y = 3x-3
substitute for y in first equation
x + 2*(3x-3) = 0
x + 6x - 6 = 0
7x = 6
x = 6/7
now substitute for x in second equation
3*(6/7) - y = 3
18/7 - y = 3
add y to both sides of = and subtract 21/7 (3) from both sides of =
y = -3/7
solution set is x = 6/7 and y = -3/7
now check the answers
substitute in first equation
x+2y=0
6/7 + 2*(-3/7) = 0
6/7 -6/7 = 0
0 = 0
substitute in second equation
3x-y=3
3*(6/7) - (-3/7) = 3
18/7 + 3/7 = 3
21/7 = 3
3 = 3
i hope this helps