x+1/x=7, find xsquare-1/xsquare
Answers
Answered by
2
Answer:
x-1/x=7
Squaring both sides,
(x-1/x)²=7²
(x)²+(1/x)²-2×x×1/x=49
x²+1/x²-2=49
x²+1/x²=49+2
x²+1/x²=51
Answered by
1
Answer:
x²+1/x² = 51
Explanation:
Given x - 1/x = 7 ---(1)
______________________
We know the algebraic identity:
a²+b²-2ab = (a-b)²
Or
a²+b² = (a-b)²+2ab
______________________
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
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