If a + b are two positive real numbers s

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Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Algebra

Question:

If a + b are two positive real numbers such that a + b = 20 and ab = 4, then the value of $a^3 + b^3$ is :

Options:

7760

240

8000

8240

Correct Answer:

7760

Explanation:

If x + y = n

then, $x^3 + y^3$ = n³ - 3 × n × xy

a + b = 20

ab = 4,

then the value of $a^3 + b^3$ = 20³ - 3 × 20 × 4

$a^3 + b^3$ = 8000 - 240 = 7760