Question 105264
Look at my lesson,"Learn to square binomials MENTALLY in just a MINUTE!"


Here, a=3a and b=4b.

furthermore,

{{{a^2=(3a)^2=9a^2}}}
{{{b^2=(4b)^2=16b^2}}}
{{{2ab=2*3a*4b=2*3*4*ab=24ab}}}

Thus,

{{{(3a- 4b)^2=9a^2-24ab+16b^2}}}

Power up,
HyperBrain!