Question

4r-81 factor completely

Answer 1

\[4r-81=2^2(\sqrt{r})^2-9^2=(2\sqrt{r}-9)(2\sqrt{r}+9)\]

Answer 2

I used formula \[a^2-b^2=(a-b)(a+b)\]

Answer 3

so thats the whole answerat the end

Answer 4

Yes, answer is \[(2\sqrt{r}-9)(2\sqrt{r}+9)\]