If p^2-q^2=12, and p+q=4 What is the value of p?
p^2 - q^2 = 12
p + q = 4
We have two equations and two unknowns, so we can solve for the values of p and q. What we'll do is substitution. We choose one equation, and choose one variable and express it in terms of the other variable. In this case, we choose the second, and express q in terms of p:
p + q = 4
q = 4 - p
And then we'll substitute this to the first equation:
p^2 - q^2 = 12
p^2 - (4-p)^2 = 12
p^2 - (16 - 8p + p^2) = 12
8p - 16 = 12
8p = 28
p = 28/8
p = 7/2
Hope this helps :)