(3а+4b)² =9а²+24ав+16в²
(2a-b)(4a²+2ab+b²)=8а³+4а²в+2ав²-4а²в-2ав²-в³=8а³-в³
9а²-16b² =(3а-4в)(3а+4в)
-5x²+10x-5 =-5(х²-2х+1)=-5(х-1)²=-5 (х-1)(х-1)
34²-21²
---------- =(34-21)(34+21)/(69-56)(69+56)=13*55/13*125=55/125=11/25
69²-56²
ответ 11/25=0,44
(2x+3)²=(2x-5)(2x+5)-2
4х²+12х+9=4х²-25-2
4х²+12х+9-4х²+25+2=0
12х+36=0
12х=-36
х= -36/12=-3