Determine unknown parameters from tangent conditions
Given a curve with unknown constants and information about a tangent line (its equation, slope, or a point it passes through), solve for the unknown parameters.
The equation of the tangent line to the graph of the cubic function $f(x) = x^3 + ax^2 + 9x + 3$ at the point $(1, f(1))$ is $y = 2x + b$. What is the value of $a + b$? (Here, $a, b$ are constants.) [4 points] (1) 1 (2) 2 (3) 3 (4) 4 (5) 5
For a cubic function $f ( x )$, the tangent line to the curve $y = f ( x )$ at the point $( 0,0 )$ and the tangent line to the curve $y = x f ( x )$ at the point $( 1,2 )$ coincide. What is the value of $f ^ { \prime } ( 2 )$? [4 points] (1) $-18$ (2) $-17$ (3) $-16$ (4) $-15$ (5) $-14$
Let $f ( x ) = x ^ { 3 } + ( a - 1 ) x ^ { 2 } + a x$. If $f ( x )$ is an odd function, then the equation of the tangent line to $y = f ( x )$ at the point $( 0,0 )$ is A. $y = - 2 x$ B. $y = - x$ C. $y = 2 x$ D. $y = x$
Let $f ( x ) = x ^ { 3 } + ( a - 1 ) x ^ { 2 } + a x$. If $f ( x )$ is an odd function, then the equation of the tangent line to the curve $y = f ( x )$ at the point $( 0,0 )$ is A. $y = - 2 x$ B. $y = - x$ C. $y = 2 x$ D. $y = x$
The tangent line to the curve $y = a \mathrm { e } ^ { x } + x \ln x$ at the point $( 1 , a \mathrm { e } )$ has equation $y = 2 x + b$ . Then A. $a = \mathrm { e } , b = - 1$ B. $a = \mathrm { e } , b = 1$ C. $a = \mathrm { e } ^ { - 1 } , b = 1$ D. $a = \mathrm { e } ^ { - 1 } , b = - 1$
7. The tangent line to the curve $y = a \mathrm { e } ^ { x } + x \ln x$ at the point $( 1 , a e )$ has equation $y = 2 x + b$ . Then A. $a = \mathrm { e } , b = - 1$ B. $a = \mathrm { e } , b = 1$ C. $a = \mathrm { e } ^ { - 1 } , b = 1$ D. $a = \mathrm { e } ^ { - 1 } , b = - 1$
6. The tangent line to the curve $y = a \mathrm { e } ^ { x } + x \ln x$ at the point $( 1 , a \mathrm { e } )$ has equation $y = 2 x + b$ . Then A. $a = \mathrm { e } , \quad b = - 1$ B. $a = \mathrm { e } , b = 1$ C. $a = \mathrm { e } ^ { - 1 } , b = 1$ D. $a = \mathrm { e } ^ { - 1 } , b = - 1$
If the tangent to the curve, $y = x ^ { 3 } + a x - b$ at the point $( 1 , - 5 )$ is perpendicular to the line, $- x + y + 4 = 0$, then which one of the following points lies on the curve? (1) $( 2 , - 2 )$ (2) $( 2 , - 1 )$ (3) $( - 2,1 )$ (4) $( - 2,2 )$
If the lines $x + y = a$ and $x - y = b$ touch the curve $y = x^2 - 3x + 2$ at the points where the curve intersects the $x$-axis, then $\frac{a}{b}$ is equal to ...
For the function $f(x) = 2x^{3} - ax^{2} + 3$, what should $a$ be so that the equation of the tangent line to the curve at some point is $y = 4$? A) $-3$ B) $-1$ C) $0$ D) $1$ E) $3$
If the line tangent to the parabola $y = x^{2} + bx + c$ at the point $x = 2$ is $y = x$, what is the sum $b + c$? A) $-2$ B) $-1$ C) $0$ D) $1$ E) $2$
Given that the function $f$ has derivative $f ^ { \prime } ( x ) = 3 x ^ { 2 }$ and the tangent line at the point $x = a ( a > 0 )$ is the line $y - 12 x + 14 = 0$, what is the value of $f ( 1 )$? A) $- 2$ B) 0 C) 1 D) 3 E) 5
A third-degree polynomial $\mathbf { P } ( \mathbf { x } )$ with leading coefficient 1 and its derivative $P ^ { \prime } ( x )$ satisfy $$P ( 0 ) = P ( 1 ) = P ^ { \prime } ( 1 ) = 0$$ Accordingly, what is the value of $P ( - 1 )$? A) 3 B) 1 C) 0 D) - 2 E) - 4
Let a and b be real numbers. In the rectangular coordinate plane, the parabola $$y = a x ^ { 2 } + b x$$ passes through the point $( 1,2 )$, and the tangent line to the parabola at this point intersects the y-axis at the point $( 0,1 )$. Accordingly, what is the product $a \cdot b$? A) - 3 B) - 2 C) - 1 D) 2 E) 4
Let a and b be real numbers, and $$f ( x ) = a \cdot \ln x + b \cdot x ^ { 2 } + 3$$ The equation of the tangent line drawn to the graph of the function at the point $(1, f(1))$ is given as $y - 2x + 1 = 0$. Accordingly, what is the product $\mathbf{a} \cdot \mathbf{b}$?\ A) $- 18$\ B) $- 16$\ C) $- 12$\ D) $- 8$\ E) $- 6$
Let a, b and c be real numbers. The equation of the tangent line to the curve $$y = \frac { a } { x + a }$$ at point $P ( a , b )$ is given in the form $$y = \frac { - x } { 8 } + c$$ Accordingly, what is the sum $a + b + c$? A) $\frac { 7 } { 4 }$ B) $\frac { 11 } { 4 }$ C) $\frac { 13 } { 4 }$ D) 2 E) 3