Question

Решите задания с картинки плиз!!! Даю много баллов!!!

Answer 1

k²+5x+64x²= (k+8x)²
k²+5x+64x²=k² +2*k*8x +(8x)^2

16k=5
k=5/16
k²=25/256

2.
((9/10)-(1/4)t⁶)²=(9/10)²-2·(9/10)·(1/4)·t⁶+(1/4)²·(t⁶)²=

=(1/16)t¹²-(9/20)t⁶+(81/100)

3.
По формуле a²-b²=(a-b)(a+b)
a=c+20d
b=20c+d

(c+20d)²-(20c+d)²=(c+20d-20c-d)(c+20d+20c+d)=(19d-19c)(21c+21d)=
=19·21(d²-c²)=399(d²-c²)