Question

if a+b+c =9 and ab +bc+ca = 40 find a²+ b²+c²

Answer 1

Heya!

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I know, due to doing few changes in the question, A² is showed to us but, I think your question is,

If a+b+c =9 and ab+bc+ca =40, find a²+b²+c²

Solution,

Given that a+b+c = 9

Then,

Square on both sides,

=> (a+b+c)² = 9²

=> a²+b²+c²+2(ab+bc+ca) =81

Putting the given values,

=> a²+b²+c² +2(40) =81

=> a²+b²+c² +80=81

=> a²+b²+c² =81-80

=> a²+b²+c² =1

Then,

=> a²+b²+c² = 1

I hope this will help you

-by ABHAY

Answer 2

We Know that....

(a+b+c)^2=a^2+b^2+c^2+2ab+2bc+2ca

so by putting the values...

9^2=a^2+b^2+c^2+40

or ...

a^2+b^2+c^2=81-40

=41