Answer:
B
Explanation:
[tex]25r^4+40r^2s+16s^2 \\ (5{r}^{2} ) {}^{2} + 40 {r}^{2} s + (4 {s})^{2} \\ (5 {r}^{2} ) {}^{2} + 2 \times 5 {r}^{2} \times 4s + (4s) {}^{2} \\ (5 {r}^{2} + 4s) {}^{2} [/tex]
In the third step we use (a+b)^2 formula.
5r^2 is a
and 4s is b
