a) x²+7x+6=x²+6x+x+6=x(x+6)+(x+6)=(x+6)(x+1)
c) x²+20x+91=x²+13x+7x+91=x(x+13)+7(x+13)=(x+13)(x+7)
d)x²-8x+15=x²-5x-3x+15=(x(x-5)-3(x-5)=(x-5)(x-3)
e)x²-4x-21=x²+7x-3x-21=x(x+7)-3(x+7)=(x+7)(x-3)
a) x²-7x+10=x²-5x-2x+10=x(x-5)-2(x-5)=(x-5)(x-2)
c)x²-12x-13=x²-13x+x-13=x(x-13)+(x-13)=(x-13(x+1)
d)x²-2x-24=x²-6x+4x-24=x(x-6)+4(x-6)=(x-6)(x+4)
e)x²-16x-17=x²-17x+x-17=x(x-17)+(x-17)=(x-17)(x+1)
6) a² =(√5-2)²=5+4-4√5=9-4√5
b²= (2+√5)²=4+5+4√5=9+4√5
c²= (3√2)²=18
observam ca a²+b²=c²
9-4√5 + 9+4√5 = 9+9=18
deci triunghiul este dreptunghic
