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jishnu r

· started a discussion

· 1 Months ago

i don't understand this , please explain the third step, how could you jump to that step its wrong , top rankers is a little disappointing , i must rethink before refereing you others

Question:

If a – b = 1, find the value of a3 – b3 + ab – (a + b)2 + (a – b)2.

Options:
A)

0

B)

1

C)

2

D)

3

Solution:

Ans: (b)

a – b = 1

a3 – b3 + ab – (a + b)2 + (a – b)2

= (a – b)(a2 + b2 + ab) + ab – a2 – b2 – 2ab + a2 + b2 – 2ab 

= a2 + b2 + 2ab – a2 – b2 – 2ab + (a – b)2

= (a – b)2

= (1)2

= 1

jishnu r

· commented

· 1 Months ago

sorry i understood now, thank u

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