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
First, divide the percent by 100. Then if the percent is not a whole number, then multiply the top and bottom by 10 for every number after the decimal point. :)
So, this question is basically asking us "If we had an x instead of a 2, would this be true?" We can try and see what we get:

So, if we want to show this we have to change the numerator or denominator in such a way that we can cancel some common factors. Notice that 
If we replace the factored numerator with the original one, we get:

Since we have an equality, this relation is proved.
Couldn't it be 54, 53 52, or 51