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Which of the following expressions is equal to 2^32-2^31-2^3

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Which of the following expressions is equal to 2^32-2^31-2^3

by Max@Math Revolution » Thu Feb 14, 2019 12:45 am

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[GMAT math practice question]

Which of the following expressions is equal to 2^32-2^31-2^30?

A. 3*2^29
B. 5*2^29
C. 2^30
D. 3*2^30
E. 2^31
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by Brent@GMATPrepNow » Thu Feb 14, 2019 7:51 am
Max@Math Revolution wrote:[GMAT math practice question]

Which of the following expressions is equal to 2^32-2^31-2^30?

A. 3*2^29
B. 5*2^29
C. 2^30
D. 3*2^30
E. 2^31
2^32 - 2^31 - 2^30 = (2^30)(2^2 - 2^1 - 1)
= (2^30)(4 - 2 - 1)
= (2^30)(1)
= 2^30

Answer: C

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by Max@Math Revolution » Sun Feb 17, 2019 5:15 pm
=>

2^{32}-2^{31}-2^{30}?
= (2^2)(2^{30})- (2^1)(2^{30})-2^{30}
= 4(2^{30})- 2(2^{30})-2^{30}
= (4-2-1)(2^{30})
=1(2^{30})=2^{30}

Therefore, the answer is C.
Answer: C
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