Test Index

Algebra and Applications Test 3

© examsnet.com

Question : 13 of 25

Marks: +1, -0

If a + b + c = 0, then the value of

\frac{a^2+b^2+c^2}{a^2-bc}

is:

0
1
2
3

Solution:

Concept:

Use the condition

a+b+c=0

to express

b+c

in terms of

a

.

Explanation:

Given:

a+b+c=0

.

So,

b+c=-a

.

Squaring both sides:

b^2+c^2+2bc=a^2

.

Add

a^2

to both sides:

a^2+b^2+c^2+2bc=2a^2

.

Thus,

a^2+b^2+c^2=2a^2-2bc=2(a^2-bc)

.

Substitute in the expression:

\frac{a^2+b^2+c^2}{a^2-bc}=\frac{2(a^2-bc)}{a^2-bc}=2

.

Answer:

The required value is

2

, so the correct option is C.

© examsnet.com

Go to Question:

Prev Question

Next Question