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# What are two numbers which multiply to make -9450 and add to make -15 ?

Jun 6, 2018

$- 105 \times 90 = - 9450$

$- 105 + 90 = - 15$

#### Explanation:

One number has to be positive and one has to be negative to give a negative product.

Factors which differ by $15$ are close to the square root of a number. They will be about $7$ bigger or smaller than the square root.

$\sqrt{9450} = 97.211 \ldots$

Try numbers less than $97$

$9450 \div 95 = 99.47 \text{ } \leftarrow$ does not work
$9450 \div 94 = 100.53 \text{ } \leftarrow$ does not work
$9450 \div 90 = 105 \text{ } \leftarrow$ These are the factors

$- 105 \times 90 = - 9450$

$- 105 + 90 = - 15$