b=7/a
a-7/a=3
a^2-7=3a
a^2-3a-7=0
a= (3+-sqrt(9+28)/2= ....
a+b=a+7/a= you do it.
If a-b=3,ab=7,then(a+b)is _______
2 answers
or,
(a-b)^2 = a^2 - 2ab + b^2 = a^2 + b^2 - 14 = 9
so, a^2+b^2 = 23
(a+b)^2 = a^2+2ab+b^2 = 23+14 = 37
(a+b) = √37
(a-b)^2 = a^2 - 2ab + b^2 = a^2 + b^2 - 14 = 9
so, a^2+b^2 = 23
(a+b)^2 = a^2+2ab+b^2 = 23+14 = 37
(a+b) = √37