Identify Function & Point: Identify the function and the point at which we need to find the limit.We have the function f(x)=3x+13−1x+4 and we need to find the limit as x approaches −4.
Substitute x=−4: Substitute x=−4 into the function to see if the limit can be directly calculated.x→−4lim3x+13−1x+4=3(−4)+13−1−4+4=−12+13−10=00We encounter an indeterminate form 0/0, which means we cannot directly calculate the limit.
Apply Algebraic Manipulation: Apply algebraic manipulation to eliminate the indeterminate form. We can multiply the numerator and the denominator by the conjugate of the denominator to rationalize it. The conjugate of 3x+13−1 is 3x+13+1.
Multiply by Conjugate: Multiply the function by the conjugate over itself.limx→−4(3x+13−1)(3x+13+1)(x+4)(3x+13+1)
Apply Difference of Squares: Apply the difference of squares formula to the denominator.The difference of squares formula is (a−b)(a+b)=a2−b2.limx→−4(3x+13)−(1)2(x+4)(3x+13+1)
Simplify Denominator: Simplify the denominator.limx→−43x+13−1(x+4)(3x+13+1)limx→−43x+12(x+4)(3x+13+1)
Cancel Common Factors: Cancel out the common factor of (x+4) in the numerator and the factor of 3(x+4) in the denominator.x→−4lim33x+13+1
Substitute x=−4: Substitute x=−4 into the simplified function to find the limit.x→−4lim[3(−4)+13+1]/3=[−12+13+1]/3=[1+1]/3=(1+1)/3=32
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