(5a-b²) (7a+2b)² (-9c+4)² (a²-4)²

Question

(5a-b²)
(7a+2b)²
(-9c+4)²
(a²-4)²

Answer 1

(5а-b)^2=25a^2-10ab+b^2
(7a+2b)^2=49a^2+28ab+4b^2
(-9c+4)^2=(4-9c)^2=16-72c+81c^2
(A^2-4)^2=a^4-8a^2+16