Question 17

If a - b = 5 and $$a^2 + b^2$$ = 97, ab = ?

Solution

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a - b = 5

Squaring both side,

$$\left(a-b\right)^2=25$$

$$a^2+b^2-2ab\ =\ 25$$

97 - 2ab = 25

2ab = 72

ab = 36.

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