Question

if a-b=-7 and ab =2find a^3-b^3​

Answer 1

Answer:

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Step-by-step explanation:

a+b=7 and ab=15

Squaring both sides,we get,

  (a+b)2=72 

=a2+b2+2ab=49                 [since(a+b)2=a2+b2+2ab]

=a2+b2+2(15)=49

=a2+b2=49−30

=a2+b2=19

Now,

  (a3+b3)

=(a+b)(a2+b2−ab)

=7(19−15)

=7(4)

=28