1. Express the condition that the curve has a stationary point at $x=1$ as an equation in terms of $a$ and $b$.
f′(x)=3x2+2ax+b
At the stationary point (1,−32), f′(1)=0:
3(1)2+2a(1)+b=0
2a+b=−3— (1)
2. Express the condition that the curve passes through the maximum point $(1, -32)$ as an equation in terms of $a, b$, and $c$.
Since the curve passes through (1,−32), we have f(1)=−32:
(1)3+a(1)2+b(1)+c=−32
1+a+b+c=−32
a+b+c=−33— (2)
3. Relate the vertical asymptote of $y = \frac{1}{f(x)}$ to the roots of $f(x)$ to form a third equation.
For the curve y=f(x)1 to have a vertical asymptote at x=5, the denominator must be zero at this point. Hence, f(5)=0.
(5)3+a(5)2+b(5)+c=0
125+25a+5b+c=0
25a+5b+c=−125— (3)
4. Solve the system of linear equations simultaneously to find $a, b$, and $c$, and state the equation of the curve.
From (1), we can express b in terms of a:
b=−3−2a
Substitute b into (2):
a+(−3−2a)+c=−33
−a−3+c=−33⟹c=a−30
Substitute both b and c into (3):
25a+5(−3−2a)+(a−30)=−125
25a−15−10a+a−30=−125
16a−45=−125
16a=−80⟹a=−5
Substitute a=−5 back into the expressions for b and c:
b=−3−2(−5)=−3+10=7
c=−5−30=−35
Thus, the equation of the curve is y=x3−5x2+7x−35.
答案y=x3−5x2+7x−35