Question

Which rational expression is undefined when a=1

Answer 1

C

Explanation:

Answer 2

`(10a + 6)/(-a^2 + 1)` is undefined at a = 1

Explanation:

Required

Which is undefined at a = 1

An expression is undefined when its denonimator equals 0.

So, we have to test the denominator of each.

(A): 7a + 7

This gives:

`= 7(1) + 7`

`= 7 + 7`

`= 14`

(B): 5a - 10

This gives:

`= 5(1) - 10`

`= 5- 10`

`= -5`

(C) -a² + 1

This gives

`-(1^2) + 1`

`= -1 + 1`

`=0`

(D) 3a²

This gives:

`= 3(1)^2`

`= 3 * 1`

`= 3`

Notice that only (C) equals 0.

Hence:

`(10a + 6)/(-a^2 + 1)` is undefined at a = 1