Question

If a +b = $7$ and ab = $10$ Find the value of $(a-b)$

Answer 1

$a+b=7$ and $ab=10$

$\Rightarrow a(7-a)=10$

$\Rightarrow 7a-a^2=10$

$\Rightarrow a^2-7a+10=0$

$\Rightarrow a^2-5a-2a+10=0$

$\Rightarrow a(a-5)-2(a-5)=0$

$\Rightarrow (a-2)(a-5)=0$

$\Rightarrow a=5,2$

$\Rightarrow b=2,5$

When $a=5,b=2$ $\Rightarrow a-b=3$

When $a=2,b=5$ $\Rightarrow a-b=-3$