Thursday, 28 September 2017

calculus - Evaluating a limit using only rationalization and algebraic methods



Evaluate (without using de L'Hôpital Rule)



limx33x2+10x+4x2+3x+15x2+11x+52x2+x+2=5817




I have to evaulate the limit of this function as it approaches 3. I have tried plugging it in but I get 0/0. Then I tried LCD, but the xy does not equal xy. Then I tried multiplying the conjugate of the denominator but after all of that I still get 0/0. I cannot use the calculator except to check my answers after completion. However when I checked there is a limit at 3 so I resorted to looking online and it gave me the answer 5817, but I cannot seem to get this answer without using L'Hôpital's rule.


Answer



Hint 1) abcd=(ab)(c+d)(c+d)(a+b)



Hint 2) 2x2+7x+3=(2x+1)(x+3), this is a+b



Hint 3) Try hint 2) with c+d.



What do you get?



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