How do you solve -x ^ { 2} + 13x + 39= - 2x ^ { 2} - 3?

1 Answer
Austte
Oct 15, 2017

x_1=-7
x_2=-6

Explanation:

Move expression to the left
-x^2+13x+39+2x^2+3=0
Collect the like terms and calculate the sum
x^2+13x+42=0
Solve the quadratic equation ax^2+bx+c=0 by discriminant formula: D=b^2-4ac
D=13^2-4×1×42=1
x_1=\frac {-b-sqrtD}{2a}

x_2=\frac {-b+sqrtD}{2a}

x_1=\frac {-13-1}{2}=-7

x_2=\frac {-13+1}{2}=-6

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