Factor Denominator: First, we need to factor the denominator of the third term to see if there are common factors with the other denominators.The third term's denominator is a quadratic expression: a2−a−12.We look for two numbers that multiply to −12 and add up to −1 (the coefficient of the middle term).The numbers −4 and +3 satisfy these conditions.So, we factor the quadratic as (a−4)(a+3).
Identify Common Denominators: Now we have the expression with common denominators identified:rac{3}{a-4} + rac{2}{a+3} - rac{21}{(a-4)(a+3)}We can now combine these fractions over a common denominator, which is (a−4)(a+3).
Combine Fractions: To combine the fractions, we adjust the numerators to have the common denominator: (a−4)(a+3)(3)(a+3)+(a−4)(a+3)(2)(a−4)−(a−4)(a+3)21
Adjust Numerators: Next, we distribute the numerators and combine like terms: (3a+9+2a−8−21)/((a−4)(a+3))
Simplify Numerator: Now we simplify the numerator by combining like terms:(3a+2a)+(9−8−21)=5a−20So the expression becomes:(a−4)(a+3)5a−20
Factor Numerator: We check if the numerator can be factored further to potentially cancel out any factors with the denominator.The numerator is 5a−20, which can be factored as 5(a−4).
Cancel Common Factor: Now we have:(5(a−4))/((a−4)(a+3))We see that the (a−4) term in the numerator and denominator can be canceled out, as long as a is not equal to 4 (since division by zero is undefined).
Final Simplified Form: After canceling out the common factor, we are left with: a+35 This is the simplified form of the original expression, assuming a=4 to avoid division by zero.
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