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C1 chapter 6 - need a calculator?

I'm currently doing the mixed exercise 6H in the Heinemann C1 textbook, and some of the inequality questions (7 and 13b), I can't see how I can do them without a calculator? When I put values into the quadratic formula, the b^2 - 4ac part is not a square number, so how can I square root this without a calculator? Could anyone tell me how to do these questions? Thanks.
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Avatar for RachJess4
RachJess4
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https://c9744745a8b49bce3d849a4d99f7984d20bc01d9.googledrive.com/host/0B1ZiqBksUHNYdXNBZzZaRVhTLTQ/Chapter%206.pdf

Exercise H, questions 7 and 13b. This is a link to the solutionbank for chapter 6; if you look, they seem to have used a calculator? Or just not explained how they managed to square root this massive number which isn't a square number without a calculator.
Original post by RachJess4
https://c9744745a8b49bce3d849a4d99f7984d20bc01d9.googledrive.com/host/0B1ZiqBksUHNYdXNBZzZaRVhTLTQ/Chapter%206.pdf

Exercise H, questions 7 and 13b. This is a link to the solutionbank for chapter 6; if you look, they seem to have used a calculator? Or just not explained how they managed to square root this massive number which isn't a square number without a calculator.


:s-smilie:

That is very puzzling. I don't think you'd be given a question that works out that way in the exam - there's no easy way of doing it mentally!

The second one is just strange. The first one, you can see that the square root of (1+16000) is roughly equal to the square root of 16000, and since 16000 is 1600*10, the square root of it is sqrt(1600) * sqrt(10) = 40root10. But then you'd need to know what root 10 roughly is.. and that'd be too unfair as well! :s-smilie:
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RachJess4
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Original post by SeanFM
:s-smilie:

That is very puzzling. I don't think you'd be given a question that works out that way in the exam - there's no easy way of doing it mentally!

The second one is just strange. The first one, you can see that the square root of (1+16000) is roughly equal to the square root of 16000, and since 16000 is 1600*10, the square root of it is sqrt(1600) * sqrt(10) = 40root10. But then you'd need to know what root 10 roughly is.. and that'd be too unfair as well! :s-smilie:


Thank you for comfirming that it's not possible without a calculator - I was going crazy trying to see if I'd missed something really obvious! :s-smilie:

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