If i = √-1, which of the following expressions shows the square of the sum (2i + 3) + (2 – 6i)?
A. 41 + 40i
B. 9 + 40i
C. 41 – 40i
D. 9 – 40i
You may be tempted to square the sum right away, but it is simpler to add the numbers before squaring them. The sum is 2 + 3 – 6i + 2i = 5 – 4i. Squaring this result produces 5 • 5 + 2 • 5 • (-4i) + (-4i) • (-4i) = 25 – 40i + 16i2 = 25 – 40i + 16(-1) = 25 – 16 – 40i = 9 – 40i. Thus the correct choice is (D).
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___________________________________________
Visit our website http://NewSATMath.org for effective Math prep books for the new SAT and online tutoring information.
Our online Math Prep system contains 1,200+ Math problems (practice questions and complete SAT Math Practice Tests).
Gain Access Now by using the PayPal link: https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=SWRYVDKLJYGYG
You will receive the username and password to your online prep account after your PayPal payment is confirmed
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