neelam2001
5

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

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 $9x^2-4*(-1)$ $\boxed{\boxed{9x^2+4}}$
$(a+b)(a-b)=a^2-b^2\\\\ (3x-2i)(3x+2i)=\\ 9x^2-4i^2\\ \\ i=\sqrt{-1}\\ i^2=-1\\ \\ 9x^2-4\cdot (-1)=9x^2+4$