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Question 7
6. (a) Given that \[ \frac{x^4 + x^3 - 3x^2 + 7x - 6}{x^2 + x - 6} \equiv x^2 + A + \frac{B}{x - 2} \]\nfind the values of the constants A and B. (b) Hence or o... show full transcript
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Answer
Calculate the derivative:
First, we find the derivative, (f'(x)), using the quotient rule:
[ f'(x) = \frac{(x^2 + x - 6)(4x^3 + 3x^2 - 6x + 7) - (x^4 + x^3 - 3x^2 + 7x - 6)(2x + 1)}{(x^2 + x - 6)^2} ]
Evaluating (f'(3)) gives a slope of the normal line at that point.
Find coordinates at (x = 3):
Substitute (x = 3) into the function to find (f(3)):
[ f(3) = \frac{3^4 + 3^3 - 3 \cdot 3^2 + 7 \cdot 3 - 6}{3^2 + 3 - 6} = \frac{81 + 27 - 27 + 21 - 6}{9 + 3 - 6} = \frac{96}{6} = 16 ]
Thus, the point is ((3, 16)).
Equation of the normal line:
The slope of the normal is the negative reciprocal of the derivative at that point:
[ \text{slope of normal} = -\frac{1}{f'(3)}. ]
Use the point-slope form of the equation:
[y - y_1 = m(x - x_1)]
where ( (x_1, y_1) = (3, 16) ) and (m) is the slope we calculated.
Final form:
Rearranging gives the equation of the normal line.
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