Square root problem

[M du Toit]

The following information was given:

a + b =7


and ab =20


Find the value of: Square root of a²+b²

I have tried to find the products of 20 that will give 7 as an answer when added but couldn't find any.

I'm also not sure if I can assume that a²+b²=7²?
Which will then give an answer of 7 if you calculate the square root? (If this is true then the info on ab=20 is not necessary??)
I am so CONFUSED...............

Any help would be greatly appreciated.
Thank you

 

[pka]

The following information was given:
a + b =7 & and ab =20
Find the value of: Square root of a²+b²

From the give you know that \(\displaystyle a^2+2ab+b^2=49.\) HOW?

 

[M du Toit]

Thank you for your response.

Why didn't I think that far!
The answer will then be 3?