Q. Find the limit as x approaches negative infinity.x→−∞lim3x4+4x8−5x3=
Identify highest power: Identify the highest power of x in both the numerator and the denominator to simplify the limit expression.In the numerator, the highest power of x is x8 inside the square root, which is equivalent to x4 when taken outside the square root. In the denominator, the highest power of x is x4.
Divide by x4: Divide both the numerator and the denominator by x4, the highest power of x in the denominator.limx→−∞(x8−5x3)/(3x4+4)=limx→−∞((x8/x4)−(5x3/x4))/((3x4/x4)+(4/x4))
Simplify expression: Simplify the expression inside the limit by canceling out the powers of x.\[\lim_{x \to -\infty}\left(\frac{\sqrt{\left(\frac{x^{\(8\)}}{x^{\(4\)}}\right)-\left(\frac{\(5\)x^{\(3\)}}{x^{\(4\)}}\right)}}{\left(\frac{\(3\)x^{\(4\)}}{x^{\(4\)}}\right)+\left(\frac{\(4\)}{x^{\(4\)}}\right)}\right) = \lim_{x \to -\infty}\left(\frac{\sqrt{x^{\(4\)}-\frac{\(5\)}{x}}}{\(3\)+\frac{\(4\)}{x^{\(4\)}}}\right)
Approach negative infinity: As \(x\) approaches negative infinity, the terms \(-\frac{5}{x}\) and \(\frac{4}{x^{4}}\) approach \(0\).\(\lim_{x \rightarrow -\infty}\left(\frac{\sqrt{x^{4}-\frac{5}{x}}}{3+\frac{4}{x^{4}}}\right) = \lim_{x \rightarrow -\infty}\left(\frac{\sqrt{x^{4}}}{3}\right)\)
Evaluate square root: Evaluate the square root of \(x^4\) as \(x\) approaches negative infinity.\(\newline\)Since \(x\) is approaching negative infinity, we must consider that the square root of \(x^4\) is the absolute value of \(x^2\), which is \(|x^2|\). However, since \(x\) is negative, \(|x^2| = x^2\) because the square of a negative number is positive.\(\newline\)\(\lim_{x \to -\infty}(\sqrt{x^{4}})/3 = \lim_{x \to -\infty}(x^2)/3\)
Determine limit: Determine the limit of \(x^2/3\) as \(x\) approaches negative infinity.\(\newline\)As \(x\) approaches negative infinity, \(x^2\) approaches positive infinity. Therefore, the limit of \(x^2/3\) as \(x\) approaches negative infinity is positive infinity.\(\newline\)\(\lim_{x \to -\infty}(x^2)/3 = +\infty\)
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