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If 2x+2y=100 and xy=18 find the value of x-y?

solve and explain

Update:

answer is +/- 8

Update 2:

i didnt write this problem but something seems awry to me...

1 Answer

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  • 9 years ago
    Favorite Answer

    i) 2x + 2y = 100; dividing by 2, x + y = 50 and xy = 18 (given)

    ii) By algebraic identity, (a - b)² = (a + b)² - 4ab

    ==> (x - y)² = 50² - 4*18 = 2500 - 72 = 2428

    iii) Taking square root of the above, |x - y| = 49.27 (nearly)

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