How do you multiply sqrt[5] * sqrt[5]?

1 Answer
Jun 21, 2016

5

Explanation:

Writing this another way we have (sqrt5)^2

(sqrt5)^2=5

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color(brown)("How squaring a square root works")

color(blue)("Point 1")
Squaring the square root has almost the same effect of not having taken the square root in the first place.

color(blue)("Point 2")
Suppose we write the square root of 5 as x.

Then (-x)xx(-x) = +5
and (+x)xx(+x)=+5

So sqrt(5) has 2 answers. These are a positive value and also a the same number but it is negative. ( +x" or "-x ).

color(blue)("Point 3")
As the whole thing is squared then it does not matter if we look at -x or +x as the answer is always going to be +5

as (-x)xx(-x)=+5" and "(+x)xx(+x)=+5