What are the excluded values for #(12a)/(a^2-3a-10)#?

1 Answer
256
Jul 31, 2017

#a=-2 and a=5#

Explanation:

In the expression #(12a)/(a^2-3a-10)# the denominator is a quadratic polynomial, that can be factored

#a^2-3a-10=a^2+(2-5)a+(-5)(2)#

#=a^2+2a-5a+(-5)(2)=(a-5)(a+2)#

Then

#(12a)/(a^2-3a-10)=(12a)/((a-5)(a+2))#

The zeroes of the polynomial in the denominator are #a=5# and #a=-2# which are the excluded values. These values are themselves excluded because you cannot divide by #0#.

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