Question

6(x²-1)-14=5x²+x = ????

Answer 1

$6(x^2-1)-14=5x^2+x \\ \\ 6x^2-6-14-5x^2-x=0 \\ \\ x^2-x-20=0 \\ \\ \Delta=(-1)^2-4.1.(-20)=1+80=81 \\ \\ x=\frac{1+-9}{2} \\ \\ x_1=5 \\ \\ x_2=-4$

Answer 2

6x²-6-14=5x²+x
6x²-5x²-x=6+14
x²-x=20
x²-x-20=0
Δ = b² -4ac
Δ = (-1)² -4 *1 * (-20)
Δ = 1 + 80
Δ = 81
x' = (-b + √∆)/ 2a
(-(-1) + 9)/2 * 1
(1 + 9)/2
10/2= 5
x'' = (-b - √∆)/ 2a
(-(-1) - 9)/2 * 1
(1 - 9)/2
-8/2= -4

S={5,-4}