Question

1). expand (4a-b+20)²

Answer 1

it can be solved by using algebraic identity (a+b+c)whole power 2
considering
a=4a
b=-b
c=20
y may calculate it
may it be helpful hint to u

Answer 2

(4a)2 + (-b)2 + (20)2 +2*4a*-b +2*-b*20 +2*20*4a
And= 16a2+b2+400-8ab-40b+160a
(2 after a and b and after all the brackets are whole square )