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If x + 2y = a and x – 2y = b, which of the following express
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24 Jan 2019, 06:52
24 Jan 2019, 06:52
1
Expert Reply
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Question Stats:
72% (01:55) correct
27% (01:50) wrong based on 107 sessions
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If \(x + 2y = a\) and \(x – 2y = b\), which of the following expressions is equal to \(xy\)?
A. \(ab\)
B. \(\frac{a+b}{2}\)
C. \(\frac{a-b}{2}\)
D. \(\frac{a^2-b^2}{4}\)
E. \(\frac{a^2-b^2}{8}\)
A. \(ab\)
B. \(\frac{a+b}{2}\)
C. \(\frac{a-b}{2}\)
D. \(\frac{a^2-b^2}{4}\)
E. \(\frac{a^2-b^2}{8}\)
Re: If x + 2y = a and x – 2y = b, which of the following express
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24 Jan 2019, 07:47
24 Jan 2019, 07:47
1
elimination is the best way to solve it,
options (b) and (c) is eliminated as they have solution only in terms of x, not xy which the question is about. Thus they are eliminated
for last 2 option, evaluate a^2-b^2 which is 8xy. Therefore, option d is the correct answer
options (b) and (c) is eliminated as they have solution only in terms of x, not xy which the question is about. Thus they are eliminated
for last 2 option, evaluate a^2-b^2 which is 8xy. Therefore, option d is the correct answer
Re: If x + 2y = a and x – 2y = b, which of the following express
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26 Jul 2020, 11:05
26 Jul 2020, 11:05
Expert Reply
\(x=a-2y\) and \(x=b+2y\)
\(a-2y=b+2y\)
\(a-b=4y\)
\(y=\frac{a-b}{4}\)
\(2y=a-x\)
\(2y=x-b\)
\(a-x=x-b\)
\(x=\frac{a+b}{2}\)
\(x \times y\)
\(\frac{a-b}{4} \times \frac{a+b}{2}\)
\(\frac{(a-b)^2}{8}\)
Answer is E
\(a-2y=b+2y\)
\(a-b=4y\)
\(y=\frac{a-b}{4}\)
\(2y=a-x\)
\(2y=x-b\)
\(a-x=x-b\)
\(x=\frac{a+b}{2}\)
\(x \times y\)
\(\frac{a-b}{4} \times \frac{a+b}{2}\)
\(\frac{(a-b)^2}{8}\)
Answer is E
