SOLUTION: find 3n^2 if n(n+5)=-4

Question 447108: find 3n^2 if n(n+5)=-4
Answer by chriswen(106) (Show Source): You can put this solution on YOUR website!
n(n+5)=-4
n^2+5n=-4
n^2+5n+4=0

Solved by pluggable solver: SOLVE quadratic equation with variable

Quadratic equation (in our case ) has the following solutons:

For these solutions to exist, the discriminant should not be a negative number.

First, we need to compute the discriminant : .

Discriminant d=9 is greater than zero. That means that there are two solutions: .

Quadratic expression can be factored:

Again, the answer is: -1, -4. Here's your graph:

Therefore n = -1 or -4.
3n^2= 3 or 48

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