Question

simplify.
(4 + 5i)(-1 - 5i)
write your answer in the form a + bi.

Explanation:

Step1: Expand using FOIL method

$(4)(-1) + (4)(-5i) + (5i)(-1) + (5i)(-5i)$

Step2: Calculate each term

$-4 -20i -5i -25i^2$

Step3: Substitute $i^2=-1$

$-4 -25i -25(-1)$

Step4: Simplify constants

$-4 -25i +25$

Step5: Combine like terms

$21 -25i$

Answer:

$21 - 25i$