Question
Download Solution PDFIf a − b = 5 and ab = 25, then the value of a3 − b3 is:
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFGiven:
If a - b = 5 and ab = 25
Formula used:
a3 - b3 = (a - b)(a2 + ab + b2)
Calculation:
a - b = 5
ab = 25
(a - b)2 = a2 - 2ab + b2
⇒ 52 = a2 - 2×25 + b2
⇒ 25 = a2 - 50 + b2
⇒ a2 + b2 = 75
a3 - b3 = (a - b)(a2 + ab + b2)
⇒ a3 - b3 = 5(75 + 25)
⇒ a3 - b3 = 5×100
⇒ a3 - b3 = 500
∴ The correct answer is option 4.
Last updated on Jun 3, 2025
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