Question

If a +b =9. ab = 10. then the value of a2 + b2is



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Answer 1

Answer:

Given,

a + b = 9 and ab = 10

Now, squaring a + b = 9 on both sides, we have

(a+b)  

2

=(9)

a  

2

+b  

2

+2ab=81

a  

2

+b  

2

+2×10=81

a  

2

+b  

2

+20=81

a  

2

+b  

2

=81−20=61

∴ a  

2

+b  

2

=61

Answer 2

a+b = 9. squaring both side

a2 + b2 +2×ab = 81

a2 + b2 + 2×10 = 81.

( put ab = 10 )

a2 + b2 + 20 = 81

a2 + b2 = 81- 20 = 61