Question

How do you multiply `(-bc+a^2)(bc+a^2)`?

Answer 1

`a^4-b^2c^2`

Let's switch the terms around in the binomials:
`(a^2+bc)(a^2-bc)`
This is a difference of squares where:
`(x^2-y^2) = (x+y)(x-y)`

If we let `x=a^2` and `y=bc`
`((a^2)^2-(bc)^2) = (a^2+bc)(a^2-bc)`