How do you solve this system of equations: x+ 3y = - 4 and 5x + 4y = 13?

1 Answer
Nov 11, 2017

Solve for either x or y and substitute the value of the variable in the other equation to solve for which variable is left.

Explanation:

x+3y = -4

5x +4y = 13

I will Solve for x first because I see smaller numbers that are easier to deal with.

x + 3y = - 4

subtract 3y from both sides to get x isolated

x = -4 - 3y

take this solution and plug it in for x in the other equation

5(-4 - 3y) + 4y = 13

distributive property

-20 -15y + 4y = 13

add like terms

-20-11y = 13

add 20 to both sides to isolate y

-11y = 33

divide both sides by a form of one to Isolate variable further

(-11y)/-11 = 33/-11

y = -3

for x=-4-3y substitute y to get x

-4-3(-3) = 5

the solutions to this system of equations are

x=5
y=-3