Practicing Success

Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Algebra

Question:

If \(\frac{(a+ b + c)}{2}\) = 16 and 2ab + 2bc + 2ca = 120, then what is the value of $4a^2 +4b^2 + 4c^2$?

Options:

1828

3368

3616

3056

Correct Answer:

3616

Explanation:

Given, If \(\frac{(a+ b + c)}{2}\) = 16

then, (a + b + c) = 2 × 16 = 32

2ab + 2bc + 2ca = 120

Now, let's square the first equation:

(a+b+c)= (32)2

 a2 + b2 + c2 + 2ab + 2bc + 2ac = 1024

Put the value of 2ab + 2bc + 2ca in the above equation,

a2 + b2 + c2 + 120  = 1024

a2 + b2 + c2  = 1024 – 120 = 904

4a2 + 4b2 + 4c2 = 4 × [ a2 + b2 + c2 ]

= 4 ×  904 = 3616