Practicing Success

Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Algebra

Question:

If a + b - c = -5 and ab - bc - ac = 10, then find the value of $a^2 +  b^2 + c^2 $

Options:

40

5

45

15

Correct Answer:

5

Explanation:

a + b - c = 5

ab - bc - ac = 10

 (a + b - c)2 = a2 + b2 + c2 + 2ab - 2bc - 2ac

= (5)= a2 + b2 + c2  + 2(ab - bc - ac)

= 25 = a2 + b2 + c2  + 2 × 10

= a2 + b2 + c2  = 25 - 20

= a2 + b2 + c2  = 5