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If x is so small such that its square an...

If `x` is so small such that its square and higher powers may be neglected, the find the value of
`((1-2x)^(1//3)+(1+5x)^(-3//2))/((9+x)^(1//2))`

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To solve the expression \[ \frac{(1-2x)^{1/3} + (1+5x)^{-3/2}}{(9+x)^{1/2}}, \] we will use the binomial expansion for small values of \(x\). Since \(x\) is small, we can neglect \(x^2\) and higher powers. ### Step 1: Expand \((1-2x)^{1/3}\) Using the binomial expansion, we have: \[ (1 + u)^n \approx 1 + nu \quad \text{for small } u. \] Here, \(u = -2x\) and \(n = \frac{1}{3}\): \[ (1-2x)^{1/3} \approx 1 + \frac{1}{3}(-2x) = 1 - \frac{2}{3}x. \] ### Step 2: Expand \((1+5x)^{-3/2}\) Similarly, we can expand \((1 + 5x)^{-3/2}\) using \(u = 5x\) and \(n = -\frac{3}{2}\): \[ (1 + 5x)^{-3/2} \approx 1 - \frac{3}{2}(5x) = 1 - \frac{15}{2}x. \] ### Step 3: Combine the expansions Now we can combine the results from Steps 1 and 2: \[ (1-2x)^{1/3} + (1+5x)^{-3/2} \approx \left(1 - \frac{2}{3}x\right) + \left(1 - \frac{15}{2}x\right). \] Combining these gives: \[ 2 - \left(\frac{2}{3} + \frac{15}{2}\right)x. \] To combine the coefficients of \(x\), we need a common denominator (which is 6): \[ \frac{2}{3} = \frac{4}{6}, \quad \frac{15}{2} = \frac{45}{6}. \] Thus, \[ \frac{2}{3} + \frac{15}{2} = \frac{4}{6} + \frac{45}{6} = \frac{49}{6}. \] So we have: \[ (1-2x)^{1/3} + (1+5x)^{-3/2} \approx 2 - \frac{49}{6}x. \] ### Step 4: Expand \((9+x)^{1/2}\) Next, we expand \((9+x)^{1/2}\): \[ (9+x)^{1/2} = 9^{1/2}\left(1 + \frac{x}{9}\right)^{1/2} \approx 3\left(1 + \frac{1}{2}\cdot\frac{x}{9}\right) = 3 + \frac{x}{6}. \] ### Step 5: Substitute into the original expression Now we substitute our expansions back into the original expression: \[ \frac{2 - \frac{49}{6}x}{3 + \frac{x}{6}}. \] ### Step 6: Simplify the expression To simplify, we can multiply the numerator and denominator by 6 to eliminate the fractions: \[ \frac{6(2 - \frac{49}{6}x)}{6(3 + \frac{x}{6})} = \frac{12 - 49x}{18 + x}. \] ### Step 7: Evaluate the limit as \(x \to 0\) As \(x\) approaches 0, we can find the value of the expression: \[ \frac{12 - 49(0)}{18 + 0} = \frac{12}{18} = \frac{2}{3}. \] ### Final Answer Thus, the value of the expression is \[ \frac{2}{3}. \]
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