Square of 3x−4y is
a) 9x2−16y2
b) 6x2−8y2
c) 9x2+16y2+24xy
d) 9x2+16y2−24xy
The correct option is (d) 9x2+16y2−24xy
Given square of (3x−4y) will be (3x−4y)2.
Now, using the identity (a−b)2=a2−2ab+b2
(3x−4y)2=(3x)2−2.3x.4y+(4y)2
=9x2−24xy+16y2