1. Aplicind metoda gruparii termenilor, descompuneti in factori ireductibili:
x³-5x²+4x-20=x(x-5)+4(x-5)=(x-5)(x+4)
2.Descompuneti in factori ireductibili polinomul:
a) ( 6x+ 3)² - ( 5X- 4)²=(6x+3+5x-4)(6x+3-5x+4)=(11x-1)(x+7)
b) 8x³- ( x- 5 )³ =(2x-x+5)[4x²+2x(x-5)+(x-5)²]=(x+5)(4x²+2x²-10x+x²-10x+25)=
=(x+5)(7x²-20x+25)