Question

I need help for algebra 2 for simplify form for example (3x-2i)(3x+2i)

Answer 1

`(a+b)(a-b)=a^2-b^2\\\\ (3x-2i)(3x+2i)=\\ 9x^2-4i^2\\ \\ i=√(-1)\\ i^2=-1\\ \\ 9x^2-4\cdot (-1)=9x^2+4`

Answer 2

Let's start...


`(3x-2i)*(3x+2i)`


`3x*3x+3x*2i-2i*3x-2i*2i`


`9x^2+6xi-6xi-4i^2`


`9x^2-4i^2`

we don't finish it yet...


`i^2=-1`

Let's replace it


`9x^2-4*(-1)`


`\boxed{\boxed{9x^2+4}}`