Question 119

If a - b = 5 and $$a^2 + b^2 = 45$$, then the value of ab is:

Solution

Given that a-b = 5 and $$a^2 +b^2 = 45 $$ then ab = ?

we know that $$ (a-b)^2 = a^2 +b^2 -2ab $$

putting the value of a-b and $$ a^2 +b^2 $$

so $$(5)^2 = 45 -2ab$$

$$\Rightarrow 25 = 45 -2ab $$

$$\Rightarrow 2ab = 20 $$

$$\Rightarrow ab =10 Ans $$

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