Question

Solve 2x2 + 20x = −38.

a. −5 ± square root 14
b.−5 ± square root 51
c. −5 ±square root 6
d.−5 ± square root 13

Answer 1

c

Explanation:

−5 ±square root 6

Answer 2

2x^2+20x=-38 divide both sides by 2

x^2+10x=-19, halve the linear coefficient, square it, than add that value to both sides of the equation, in this case add (10/2)^2=25...

x^2+10x+25=6 now the left side is a perfect square

(x+5)^2=6 take the square root of both sides

x+5=±√6 subtract 5 from both sides

x=-5±√6 (so answer c.)