Question

Approximate -10 + √30 to the nearest tenth.
O-5.5
O-4.5
04.5
O5.5

Answer 1

(b) -4.5

Explanation:

Choosing the correct answer here is not the same as knowing what the correct value is.

Estimate

You know that √30 < √100 = 10, so the sum must be negative. That is, 10 subtracted from a positive number less than 10 will give a negative result.

You know that 25 < 30 < 36, so √25 < √30 <√36. That is, √30 will be between 5 and 6. If we say √30 ≈ 5.5, then the sum is ...

-10 +√30 ≈ -10 +5.5 = -4.5

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Additional comment

Of course, a calculator can tell you the value to the desired precision.