any strategy to these approximations? I knew that it would be 13 if it was the sq root of 9 instead of 10 but I then expect it to be a bit higher
Thanks!
Thanks!
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Apply the formula (a+b)^2 = a^2 + 2ab + b^2
Hence,
(sqrt(2) + sqrt(5))^2
= (sqrt(2))^2 + 2(sqrt(2))(sqrt(5)) + ((sqrt(5))^2
= 2 + 2(sqrt(10)) + 5
= 7 + 2(sqrt(10))
Once you get to this, you need not calculate the exact value of sqrt(10).
Sqrt(9) is 3.. so sqrt(10) would be just over 3. So, we can assume sqrt(10) as 3, since the problem asks for approximate value.
So, the equation becomes = 7 + 2(3) = 13, C it is.
Hope this helps. Please share if you have any better ideas.
