Question

13. If a + b = 9 and a^2 -b^2=27 find the value of ab?​

Answer 1

Step-by-step explanation:

(a+b)(a-b)=27,(a-b)=3

4ab=(a+b)²-(a-b)²

4ab=81-9

4ab=72

ab=18

Answer 2

Answer:

solution,

a+b=9

a^2-b^2=27

ab=?

We know,

a^2-b^2=27

by using formula of a^2-b^2

or,(a+b)(a-b)=27

or,9(a-b)=27

or,(a-b)=27-9

or,(a-b)=18

Now,

squaring on boths sides,we get,

or,(a-b)^2=18^2

or,a^2-2ab+b^2=324

or,a^2+b^2-2ab=324

or,(a+b)^2-2ab-2ab=324

or,9^2-4ab=324

or,81-4ab=324

or,-4ab=324-81

or,ab=243/-4

ab=-60.75

Step-by-step explanation:

I think the answer will be-60.75.

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