Question

Как разложить на множители трехчлен

a) x^2 + 3x - 54
b) x^2 -2x - 80
c) x^2 + 10x + 21
d) 4x^2 - 12x + 9

Answer 1

Объяснение:

a) x^2 + 3x - 54 = x^2 + 9x - 6x - 54 = x(x - 6)+9(x-6) = (x - 6)(x + 9)

b) x^2 - 2x - 80 = x^2 - 10x + 8x - 80 = x(x+8)-10(x+8) = (x - 10)(x + 8)

c) x^2 + 10x + 21 = x^2 + 3x + 7x + 21 = x(x+7)+3(x+7) = (x + 3)(x + 7)

d) 4x^2 - 12x + 9 = (2x)^2 - 12x + 3^2 = (2x - 3)^2

Answer 2

1) D = 15

X1=-3+15/2=6

X2=-3-15/2=-9