How do you simplify and restricted value of (a^2 - a - 2)/(a^2 - 13a + 30)a2a2a213a+30?

1 Answer
May 19, 2017

frac((a + 1)(a - 2))((a - 3)(a - 10))(a+1)(a2)(a3)(a10); a ne 3, 10a3,10

Explanation:

We have: frac(a^(2) - a - 2)(a^(2) - 13 a + 30)a2a2a213a+30

Let's factorise both the numerator and the denominator using the "middle-term break":

= frac(a^(2) + a - 2 a - 2)(a^(2) - 3 a - 10 a + 30)=a2+a2a2a23a10a+30

= frac(a(a + 1) - 2(a + 1))(a(a - 3) - 10(a - 3))=a(a+1)2(a+1)a(a3)10(a3)

= frac((a + 1)(a - 2))((a - 3)(a - 10))=(a+1)(a2)(a3)(a10)

Now let's evaluate the restricted values of aa.

The denominator of the fraction can never be equal to zero:

Rightarrow (a - 3)(a - 10) ne 0(a3)(a10)0

Using the null factor law:

Rightarrow a - 3 ne 0, a - 10 ne 0a30,a100

Rightarrow a ne 3, a ne 10a3,a10

therefore frac(a^(2) - a - 2)(a^(2) - 13 a + 30) = frac((a + 1)(a - 2))((a - 3)(a - 10)); a ne 3, 10