Question

Descompuneti in factori
a)x²-3x-4
b)x²+4x-5
c)x²+2x-3
d)x²-6x-7
e)x²-8x-20
f)x²+7x-18
g)x²+x-2
h)x²-x-6
i)x²-x-2

dau coroana si 30 de puncte

Answer 1

a) x² - 3x - 4 = x² - 4x + x - 4 = x(x-4) + 1(x-4) = (x-4)(x+1)
b) x² + 4x - 5 = x² + 5x - x - 5 = x(x+5) - 1(x+5) = (x+5)(x-1)
c) x² + 2x - 3 = x² + 3x - x - 3 = x(x+3) - 1(x+3) = (x+3)(x-1)
d) x² - 6x - 7 = x² - 7x + x - 7 = x(x-7) + 1(x-7) = (x-7)(x+1)
e) x² - 8x - 20 = x² - 2x + 10x - 20 = x(x-2) - 10(x-2) = (x-2)(x-10)
f) x² + 7x - 18 = x² + 9x - 2x - 18 = x(x+9) - 2(x+9) = (x+9)(x-2)
g) x² + x - 2 = x² + 2x - x - 2 = x(x+2) - 1(x+2) = (x+2)(x-1)
h) x² - x - 6 = x² - 3x + 2x - 6 = x(x-3) + 2(x-3) = (x-3)(x+2)
i) x² - x - 2 = x² - 2x + x - 2 = x(x-2) + 1(x-2) = (x-2)(x+1)