Question

x²+3x-40 = -x²+15x+40

Answer 1

Boa noite Carolina!

$x {}^{2} + 3x - 40 = - x {}^{2} + 15x + 40$

$x {}^{2} + 3x - 40 + x {}^{2} - 15x - 40 = 0$

$2x {}^{2} + 3x - 40 - 15x - 40 = 0$

$2x {}^{2} - 12x - 40 - 40 = 0$

$2x {}^{2} - 12x - 80 = 0$

$x {}^{2} - 6x - 40 = 0$

$x {}^{2} + 4x - 10x - 40 = 0$

$x \times (x + 4) - 10x - 40 = 0$

$x \times (x + 4) - 10(x + 4) = 0$

$(x + 4) \times (x - 10) = 0$

$x + 4 = 0 \\ x - 10 = 0$

$x = - 4 \\ x = 10$

$x1 = - 4 \\ x2 = 10$

Espero ter ajudado!

Answer 2

x^2+3x-40=-x^2+15x+40
x^2+3x-40+x^2-15x-40=0
2x^2-12x-80=0
x^2-6x-40=0
/\=(-6)^2-4.1.(-40)
/\=36+160
/\=196
x=-(-6)+-\/`196/2.1
x=6+-14/2
x'=6+14/2
x'=20/2
x'=10
x"=6-14/2
x"=-8/2
x"=-4

x' = 10
x" = -4