If x + 1/y = 2, then what is the value of {(x2y + 4xy + x)(2 – x)}/(2xy – x2y)?
If x + 1/y = 2, then what is the value of {(x2y + 4xy + x)(2 – x)}/(2xy – x2y)? Correct Answer 6
x + 1/y = 2
xy + 1 = 2y ----(1)
= {(x2y + 4xy + x)(2 – x)} / (2xy – x2y)
= {x(xy + 4y + 1)(2 – x)} / {x(2y – xy)}
= {(xy + 4y + 1)(2 – x)} / {y(2 – x)}
= (xy + 4y + 1) /y
From equation (1):
= (2y + 4y) /y
= 6y/y
= 6
Smart trick
Put, x = y = 1
Hence, x + 1/y = 1 + 1 = 2 (satisfied)
Now, {(x2y + 4xy + x)(2 – x)}/(2xy – x2y)
= (1 + 4 + 1)(2 - 1)/(2 - 1)
= 6
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Feb 20, 2025