Question

If x-1/x=7, then the value of x² + 1/x sq, is
(d) 52
(a) 49
(b) 50
(c) 51​

Answer 1

Answer:

x²+1/x² = 51

Explanation:

Given x - 1/x = 7 ---(1)

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We know the algebraic identity:

a²+b²-2ab = (a-b)²

Or

a²+b² = (a-b)²+2ab

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Now,

x²+1/x²

= (x-1/x)²+2*x*(1/x)

= (x-1/x)²+2

= 7²+2 [ from (1)]

= 49+2

= 51

Therefore,

x²+1/x² = 51

•••••

[option (C)]