simplify. 5i(-5i) write your answer in the form a + bi.

Explanation:

Step1: Multiply the coefficients

$5\times(- 5)=-25$.

Step2: Multiply the imaginary units

$i\times i = i^{2}$. Since $i^{2}=-1$, then $-25\times i^{2}=-25\times(-1)$.

Step3: Calculate the result

$-25\times(-1) = 25+0i$.

Answer:

$25 + 0i$