If $a^3 + b^3 = 62$ and $ a + b = 2$, th

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Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Algebra

Question:

If $a^3 + b^3 = 62$ and $ a + b = 2$, then the value of ab is:

Options:

-9

-6

Correct Answer:

-9

Explanation:

a + b = 2

a³ + b³ = 62

(a + b)³ = a³ + b³ + 3ab(a + b)

Cubing the given equation on both the sides,

(a + b)³ = 2³

= a³ + b³ + 3ab(a + b) = 8

= 62 + 3ab (2) = 8

= 6ab = 8 – 62

= 6ab = -54

ab = -9