Evaluate the expression and write the result in the form a+bi

Question

Evaluate the expression (-2-√(-4)))(-4+√(-25)) and write the result in the form a+bi

the real number A equals?

the real number B equals?

 

Answer 1

Hi Dalia,

 

(-2-√-4)(-4+√-25)=-2(-4+√-25)-√-4(-4+√-25)

 

                           =-2(-4+5i)-2i(-4+5i)

 

                          =8-10i+8i-10i²

                          =8-2i+10     (i²=-1)

                          =18-2i 

Answer 2

( - 2 - √-4 ) ( -4 + √-25 ) =

 

( -2 - 2i) ( - 4 + 5i) =

 

 ( -2 - 2i ) (-4) + 5i( - 2 - 2i) =

 

 

8 + 8i - 10 i +10 = 18 -2i