Question

Using the identity $(x+a)(x+b)=x^2+(a+b)x+ab$, find out the following product:
$(8x-5)(8x-2)$

Answer 1

using $(x+a)(x+b)=x^2+ba+(a+b)x$

For the above expression, keeping $a=8x$ and $b=2$, we get

$(8x-5)(8x-2)=(8x{)}^2+10+(-5-2)8x=64x^2+10-56x$