Question

if a^2+b^2=13and ab=6 find a+b​

Answer 1

(I) (a+b)^2= a^2+b^2+2ab

= 13+2×6

=25

(a+b) = √25 = ±5

(2) (a-b)^2= a^2+b^2 - 2ab

= 13 - 2×6

= 1

(a-b) = √1= ±1