SOLUTION: Please help. I cannot figure just what formula to use. (Using Nonlinear Systems) Solving problems using a System of of Equation in two variables. Unknown numbers. Find two

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Question 252517: Please help. I cannot figure just what formula to use.
(Using Nonlinear Systems) Solving problems using a System of of Equation in two variables.
Unknown numbers. Find two numbers whose sum is 10 and whose squares differ by 20.
Answer( 6 and 4)

Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
there is no formula but we must make two equations with two unknowns
let n and m be the two numbers
n+m=10
n^2-m^2=20
n=10-m
substitute
(10-m)^2-m^2=20
100-20m+m^2-m^2=20
fortunately the squared variables are cancelled out
80-20m=0
80=20m
4=m
n=10-m
n=10-4=6