Practicing Success

Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Algebra

Question:

If a + b + c = 2

\(\frac{1}{a}\) + \(\frac{1}{b}\) + \(\frac{1}{c}\) = 0

ac = \(\frac{4}{b}\)  ,  a3 + b3 + c3 = 28, then

Find a2 + b2 + c2

Options:

7

8

9

10

Correct Answer:

8

Explanation:

Formula used → a3 + b3 + c3 - 3abc = (a + b + c) (a2 + b2 + c- ab - bc - ca)......(i)

If ac = \(\frac{4}{b}\) ⇒ acb = 4

Now; \(\frac{1}{a}\) + \(\frac{1}{b}\) + \(\frac{1}{c}\) = 0

\(\frac{bc + ca + ab}{abc}\) = 0

So, bc + ca + ab = 0

From (i)

28 - 3 (4) = (2) (a2 + b2 + c- 0)

16 = 2(a2 + b2 + c2)

a2 + b2 + c2 = 8