Question

a^2+(3a-b)^2=
(a-4)^2+a(a+8)=
(a-c)*(a+c)-(a-2c)^2=

Answer 1

1) a²+(3a-b)²=a²+9a²-6ab+b²=10a²-6ab+b²
2) (a-4)²+a(a+8)=a²-8a+16+a²+8a=2a²+16
3) (a-c)*(a+c)-(a-2c)²=a²-c²-a²+4ac-4c²=-5c²+4ac