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Derivative of a polynomial using linearity rules

Let f(x)=5x3−4x2+7x−2f(x) = 5x^3 - 4x^2 + 7x - 2. Find f′(x)f'(x).

Hint

Differentiate the function term by term. Apply the power rule to each term, use the constant multiple rule to handle the coefficients, and remember that the derivative of a constant is 0.

Step-by-step solution

Differentiate each term separately using the sum/difference rule: f′(x)=ddx[5x3]−ddx[4x2]+ddx[7x]−ddx[2]f'(x) = \frac{d}{dx}[5x^3] - \frac{d}{dx}[4x^2] + \frac{d}{dx}[7x] - \frac{d}{dx}[2]. For each term, apply the power rule ddx[xn]=nxn−1\frac{d}{dx}[x^n] = nx^{n-1} together with the constant multiple rule ddx[cf(x)]=cf′(x)\frac{d}{dx}[cf(x)] = cf'(x).

Computing each piece: ddx[5x3]=5(3x2)=15x2\frac{d}{dx}[5x^3] = 5(3x^2) = 15x^2, ddx[4x2]=4(2x)=8x\frac{d}{dx}[4x^2] = 4(2x) = 8x, ddx[7x]=7\frac{d}{dx}[7x] = 7, and ddx[2]=0\frac{d}{dx}[2] = 0 since the derivative of a constant is zero. Combining these gives f′(x)=15x2−8x+7f'(x) = 15x^2 - 8x + 7.

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