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Difficulty:
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Question Stats:
79% (01:24) correct
21%
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\(99,999^2 - 1^2 =\)
A. \(10^{10} - 2\)
B. \((10^5 – 2)^2\)
C. \(10^4(10^5 – 2)\)
D. \(10^5(10^4 – 2)\)
E. \(10^5(10^5 – 2)\)
A. \(10^{10} - 2\)
B. \((10^5 – 2)^2\)
C. \(10^4(10^5 – 2)\)
D. \(10^5(10^4 – 2)\)
E. \(10^5(10^5 – 2)\)
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4112019
99,999^2 - 1^2 =
A. 10^10 - 2
B. (10^5 – 2)^2
C. 10^4(10^5 – 2)
D. 10^5(10^4 – 2)
E. 10^5(10^5 – 2)
Apply \(a^2-b^2=(a+b)(a-b)\):
\(99,999^2-1^2 =(99,999+1)(99,999-1)=10^5(10^5-1-1)=10^5(10^5-2)\)
Answer: E.
Hope it's clear.
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4112019
Using the difference of squares, we have:
(99,999 + 1)(99,999 - 1)
(100,000)(99,998)
(100,000)(100,000 - 2)
10^5(10^5 - 2)
Answer: E
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(99,999)^2 - (1)^2 = (100,000 -1)^2 - (1)^2 = (100,000)^2 - 2*100,000 + 1-1=(10^5)^2 - 2*(10^5) = 10^10 - 2*(10^5)=10^5(10^5 - 2) Answer E
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4112019
99,999^2 - 1^2
a^2-b^2= (a+b) (a-b)
(99,999+1) (99,999-1)
10^5 (99,998)
10^5 (10^5-2)
E is the answer
4112019
99,999^2 - 1^2 =
(99999 - 1) (99999 + 1)
99998 * 100000
(10^5 - 2) * 10^5
Hence (E)
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4112019
\(99,999^2 - 1^2\) \(=\) \((99,999 - 1)(99,999 + 1)\)
Or, \(99,999^2 - 1^2\) \(=\) \(99,99800000\)
Or, \(99,999^2 - 1^2\) \(=\) \(100,00000000 - 200000\)
Or, \(99,999^2 - 1^2\) \(=\) \(10^5(10^5 – 2)\), Answer must be (E)
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99,999^2 - 1^2
\(a^2\)-\(b^2\)= (a+b) (a-b)
(99,999+1) (99,999-1)
\(10^5\) (99,998)
\(10^5\) (\(10^5\)-2)
Ans: E
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\(a^2\)-\(b^2\)= (a+b) (a-b)
(99,999+1) (99,999-1)
\(10^5\) (99,998)
\(10^5\) (\(10^5\)-2)
Ans: E
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Difference of squares = \(a^2 - b^2 = (a+b)(a-b)\)
\(= (99,999 + 1) (99,999 - 1)\)
\(= 10^5 * (10^5 - 2)\)
Answer is. E
\(= (99,999 + 1) (99,999 - 1)\)
\(= 10^5 * (10^5 - 2)\)
Answer is. E
4112019
You can also use (a-b)^2 here.
\(99,999^2 - 1^2\\
= (10^5 - 1)^2 - 1^2\\
= 10^{10} - 2*10^5 + 1 - 1^2\\
= 10^{10} - 2*10^5\\
= 10^5(10^5 - 2)\)
Answer (E)
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I've had this question on a Official Practice GMAT, and the correct anwer is D) 10^5(10^4 -2). How so?
Bunuel
adipiscimagni
E is correct for this question as shown above.
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