the sum of q number and it's reciprocal is 3, find the number
Answers
Answer:
Reciprocal means 1 divided by that number. For example, the reciprocal of 2 is 1/2.
So lets call the number we are trying to find x.
x + 1/x = 3
so, now rearrange x and 1/x so they have the same denominator (the bottom part of the fraction). To do this, we can say that x = x/1. Times the top and bottom by x. That gives x2/x.
so...
x2/x + 1/x = 3
now we can add the fractions.
(x2+1) / x = 3
Times each side of the equation by x.
x2+1 = 3x
x2 -3x +1 = 0
This is a quadratic equation that we can solve, to find x.
Then you can use the quadratic formula to find x. If you want to see how this works, go to:
but it gives us the answers:
x = (3+sqrt5)/2
or (3-sqrt5)/2
(sqrt 5 means the square root of 5)
which come out as 2.618 (to 3 decimal places)
and 0.382 (to 3 decimal places)
and you can check: when you add them to their reciprocal, you get 3
Answer:
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