Question

If a^2 + b^2=100 ,
ab=4
then a + b =?​

Answer 1

$(a+b)^2=a^2+2ab+b^2\\(a+b)^2=100+2\cdot 4=108\\a+b=\sqrt{108} \vee a+b=-\sqrt{108}\\a+b=2\sqrt{27} \vee a+b=-2\sqrt{27}$