СР-19 Формулы сокращённого умножения. Вариант Б-4

1
$1)121a^2-154ab+49b^2=(11a-7b)^2$
$2)81a^4b^2+144a^2bc^2+64c^4=(9a^2b+8c^2)^2$
$3)27a^3+216a^2b+576ab^2+512b^3=(3a+8b)^3$
$4)27x^6y^{12}-405x^4y^9+225x^2y^6-125y^3=(3x^2y^4-5y)^3$
2
1)25-16a²=0
16a²=25
a²=25/16
a=-5/4 U a=5/4
2)0,09x²-4=0
0,09x²=4
x²=4:0,09
x²=400/9
x=-20/9 U x=20/9
3)16b²-40b+25=0
(4b-5)²=0
4b-5=0
4b=5
b=5/4
4)27a³-135a²+225a-125=0
(3a-5)³=0
3a-5=0
3a=5
a=5/3
3
1)(64²-29²)/(46²-16²)=(64-29)(64+29)/[(46-16)(46+16)]=35*93/(30*62)]=
=(7*3)/(6*2)=(7*1)/(2*2)=7/4
2)(38³-22³)/16 +38*22=(38-22)(38²+38*22+22²)/16+38*22=
=16(38²+38*22+22²)/16+38*22=38²+38*22+22²+38*22=
=38²+2*38*22+22²=(38+22)²=60²=3600