Question

If a + b = 10 and ab = 21, then the value of (a - b)2 is

Answer 1

Hi_______

but if u find the value of (a-b)2

in snap i found the value of
(a-b)^2=16

a-b=4
2(a-b)=2*4=8

i dont understand ur question clear ,

i solve assuming both expections.

hope u got it

Answer 2

Thanks for the question!

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It is given that a+b = 10 and ab = 21.

Since (a+b)2 = a2 +2ab +b2,

While substituting we get

102 = a2 + 2(21)+b2.
i.e. 100 = a2 + b2 + 42,

a2+ b2= 100 -42 = 58.

Now,
a2 + b2 = (a − b)2 + 2ab

 (a − b)2  = [a2 + b2] - 2ab


 (a − b)2  = 58 - 2X21
                = 58 - 42
                =  16


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Hope it helps and solves your query!!