if a-b=3 and ab=4 find a3-b3
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squaring
(a-b)2=a2+b2-2ab
9=a2+b2-2ab
a2+b2=1
Now
a3-b3=(a-b)(a2 +b2+ab)
putting the value
3 (1+4)
3×5
15
Hope it will help you.
(a-b)2=a2+b2-2ab
9=a2+b2-2ab
a2+b2=1
Now
a3-b3=(a-b)(a2 +b2+ab)
putting the value
3 (1+4)
3×5
15
Hope it will help you.
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