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5. (5pts) find the slope ( y^{prime}(x) ) of the tangent line to the cu…

Question

  1. (5pts) find the slope ( y^{prime}(x) ) of the tangent line to the curve of ( y(x)=a x^{2}+b x+c ) where ( a, b ), and ( c ) are constants. recall that the slope of the tangent line is given by ( y^{prime}(x)=\frac{y(x+delta x)-y(x)}{delta x} ) then let ( delta x

ightarrow 0 ) show all of your work. 6. (5pts) similarly, the velocity ( v(t) ) is the instantaneous rate of change (slope of the tangent line) of ( x(t) ) ( v(t)=\frac{x(t+delta t)-x(t)}{delta t} ) then let ( delta t
ightarrow 0 ) find the velocity ( v(t) ) given that ( x(t)=3 t^{2}+4 t ).

Explanation:

Problem 5

Step1: Substitute \(y(x)\) into the formula

Given \(y(x)=Ax^{2}+Bx + C\), then \(y(x+\Delta x)=A(x + \Delta x)^{2}+B(x+\Delta x)+C\).
Expand \(y(x+\Delta x)\):

$$ LATEXBLOCK0 $$

Now, \(y(x+\Delta x)-y(x)=(Ax^{2}+2Ax\Delta x+A\Delta x^{2}+Bx + B\Delta x+C)-(Ax^{2}+Bx + C)\)

$$ LATEXBLOCK1 $$

Step2: Calculate \(\frac{y(x+\Delta x)-y(x)}{\Delta x}\)

$$ \frac{y(x+\Delta x)-y(x)}{\Delta x}=\frac{2Ax\Delta x+A\Delta x^{2}+B\Delta x}{\Delta x}=2Ax + A\Delta x+B $$

Step3: Take the limit as \(\Delta x

ightarrow0\)

$$ y^{\prime}(x)=\lim_{\Delta x ightarrow0}\frac{y(x+\Delta x)-y(x)}{\Delta x}=\lim_{\Delta x ightarrow0}(2Ax + A\Delta x+B) $$

Since \(\lim_{\Delta x
ightarrow0}(A\Delta x) = 0\), we have \(y^{\prime}(x)=2Ax + B\)

Step1: Substitute \(x(t)\) into the formula

Given \(x(t)=3t^{2}+4t\), then \(x(t+\Delta t)=3(t + \Delta t)^{2}+4(t+\Delta t)\)
Expand \(x(t+\Delta t)\):

$$ LATEXBLOCK0 $$

Now, \(x(t+\Delta t)-x(t)=(3t^{2}+6t\Delta t+3\Delta t^{2}+4t + 4\Delta t)-(3t^{2}+4t)\)

$$ LATEXBLOCK1 $$

Step2: Calculate \(\frac{x(t+\Delta t)-x(t)}{\Delta t}\)

$$ \frac{x(t+\Delta t)-x(t)}{\Delta t}=\frac{6t\Delta t+3\Delta t^{2}+4\Delta t}{\Delta t}=6t + 3\Delta t+4 $$

Step3: Take the limit as \(\Delta t

ightarrow0\)

$$ v(t)=\lim_{\Delta t ightarrow0}\frac{x(t+\Delta t)-x(t)}{\Delta t}=\lim_{\Delta t ightarrow0}(6t + 3\Delta t+4) $$

Since \(\lim_{\Delta t
ightarrow0}(3\Delta t) = 0\), we have \(v(t)=6t + 4\)

Answer:

\(y^{\prime}(x)=2Ax + B\)

Problem 6