Решите уравнения : 121a² - 25 = 0 (1 - 2b)(1+2b)+4b(b-2)=49 (x-2)³+(x+2)³=2(x-3)(x²+3x+9)

1) 121a²  - 25 =0
(11a-5)(11a+5)=0
11a-5=0
a=5/11
11a+5=0
a=-5/11
2) (1-2b)(1+2b)+4b(b-2)=49
(1-4b² )+4b² -8b=49
1-8b=49
48=-8b
b=-6
3)(x-2)³+(x+2)³=2(x-3)(x²+3x+9)
(x³-6x²+12x-8)+(x³+6x²+12x+8)=(2x-6)(x²+3x+9)=2x³+6x²+18x-6x²-18x-54=2x³-54
2x³+24x=2x³-54
x³+12x=x³-27
x³+12x-x³+27=0
12x=-27
x=-27/12=-2.25