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Express (4 - 5i)(5 + 5i) in the form a + bi, where a and b are integers and i^2 = -1.

 Sep 17, 2021
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Express (4 - 5i)(5 + 5i) in the form a + bi, where a and b are integers and i^2 = -1.   

 

Just multiply it out, then combine like terms.  

 

(4 - 5i)(5 + 5i)  =  20 + 20i – 25i – 25i2   ( remember since i2 is –1 then –25i2 becomes +25 )  

 

                            20 – 5i + 25   

 

                            45 – 5i  

.

 Sep 17, 2021

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