Question

(36-9dsquare) (36-dsquare)

Answer 1

(36-9d^2)(36-d^2)

to factorise:

(6^2-(3d)^2)(6^2-(3d)^2)

=(6+3d)(6-3d(6+d)(6-d)

if we want to simplify:

(36^2-36*9d^2-36d^2+d^4)

=1296-324d^2-36d^2+d^4

=d^4-360d^2+1296

Answer 2

(36-9d²)(36-d²)
(36×36)-(36d²)-(36×9d²)+9d⁴
1296-36d²-324d²+9d⁴
9d⁴-36d²-324d²+1296
9d²(d²-4)-324(d²-4)
(d²-4)(9d²-324)
d=±2 or d=±6