Practicing Success

Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Algebra

Question:

If a - b = 18 and $a^3 - b^3 = 324$, then find ab.

Options:

-102

103

105

-104

Correct Answer:

-102

Explanation:

If a - b = 18

$a^3 - b^3 = 324$,

then find ab = ?

(a - b)3 = a3 - b3 - 3ab(a-b)

(18)3 = 324 - 3ab(18)

5832 - 324 = -54ab

5508 = -54ab

ab = -102