Can I please have help as to how to solve a system using substitution? I have a quiz coming up and I want to ace it. :) Thank you.
2 answers
@Ms.Sue could you please help me?
If you are asked to use substitution, usually one of the equations has a variable with coefficient of 1
e.g. 3x + y = 8
solve that equation for y (or x) and sub it into the other equation.
e.g.
5x - 7y = 59
x + 4y = 1
from the 2nd, notice that the x term has a coefficient of 1, so solve for x
x = 1 -4y
plug that into the other equation:
5(1-4y) - 7y = 59
5 - 20y - 7y = 59
-27y = 54
y = -2
now back into x = 1 - 4y
x = 1 -4(-2) = 9
x = 9, y = -2
e.g. 3x + y = 8
solve that equation for y (or x) and sub it into the other equation.
e.g.
5x - 7y = 59
x + 4y = 1
from the 2nd, notice that the x term has a coefficient of 1, so solve for x
x = 1 -4y
plug that into the other equation:
5(1-4y) - 7y = 59
5 - 20y - 7y = 59
-27y = 54
y = -2
now back into x = 1 - 4y
x = 1 -4(-2) = 9
x = 9, y = -2
1 answer