The Equation of the Tangent to the Curve at the Origin

Oct 13, 2025 by wbrum.org 142 views

Introduction

In this article, we will explore the problem of finding the value of $a$ and $b$ in the equation $y = ax^5$ , given that $\frac{dy}{dx} = \frac{3}{2}$ at $(1, b)$ . We will also derive the equation of the tangent to the curve at the origin.

The Derivative of y = ax^5

To find the derivative of $y = ax^5$ , we will use the power rule of differentiation, which states that if $y = x^n$ , then $\frac{dy}{dx} = nx^{n-1}$ .

Using this rule, we can differentiate $y = ax^5$ as follows:

\frac{dy}{dx} = 5ax^4

Finding the Value of a

We are given that $\frac{dy}{dx} = \frac{3}{2}$ at $(1, b)$ . Substituting $x = 1$ into the derivative, we get:

\frac{dy}{dx} = 5a(1)^4 = 5a

Equating this to $\frac{3}{2}$ , we get:

5a = \frac{3}{2}

Solving for $a$ , we get:

a = \frac{3}{10}

Finding the Value of b

Now that we have found the value of $a$ , we can find the value of $b$ by substituting $x = 1$ into the equation $y = ax^5$ :

y = a(1)^5 = a = \frac{3}{10}

Therefore, the value of $b$ is $\frac{3}{10}$ .

The Equation of the Tangent to the Curve at the Origin

To find the equation of the tangent to the curve at the origin, we need to find the slope of the tangent line at the origin. We can do this by finding the derivative of the equation $y = ax^5$ at $x = 0$ .

Using the power rule of differentiation, we can differentiate $y = ax^5$ as follows:

\frac{dy}{dx} = 5ax^4

Substituting $x = 0$ into this derivative, we get:

\frac{dy}{dx} = 5a(0)^4 = 0

Therefore, the slope of the tangent line at the origin is $0$ .

The Equation of the Tangent Line

Now that we have found the slope of the tangent line at the origin, we can write the equation of the tangent line in the form $y = mx + b$ , where $m$ is the slope and $b$ is the y-intercept.

Since the slope of the tangent line at the origin is $0$ , the equation of the tangent line is:

y = 0x + b

Substituting $x = 0$ into the equation $y = ax^5$ , we get:

y = a(0)^5 = 0

Therefore, the equation of the tangent line is:

y = 0

Conclusion

In this article, we have found the value of $a$ and $b$ in the equation $y = ax^5$ , given that $\frac{dy}{dx} = \frac{3}{2}$ at $(1, b)$ . We have also derived the equation of the tangent to the curve at the origin.

The value of $a$ is $\frac{3}{10}$ , and the value of $b$ is $\frac{3}{10}$ . The equation of the tangent line is $y = 0$ .

References

[1] Calculus, James Stewart, 8th edition, Brooks Cole, 2015.
[2] Differential Calculus, Michael Spivak, Publish or Perish, 2008.

Glossary

Derivative: A measure of how a function changes as its input changes.
Power Rule: A rule for differentiating functions of the form $y = x^n$ .
Tangent Line: A line that just touches a curve at a single point.

Introduction

In our previous article, we explored the problem of finding the value of $a$ and $b$ in the equation $y = ax^5$ , given that $\frac{dy}{dx} = \frac{3}{2}$ at $(1, b)$ . We also derived the equation of the tangent to the curve at the origin.

In this article, we will answer some frequently asked questions related to this problem.

Q: What is the derivative of y = ax^5?

A: The derivative of $y = ax^5$ is $\frac{dy}{dx} = 5ax^4$ .

Q: How do I find the value of a?

A: To find the value of $a$ , you need to substitute $x = 1$ into the derivative and equate it to $\frac{3}{2}$ . This will give you the equation $5a = \frac{3}{2}$ . Solving for $a$ , you get $a = \frac{3}{10}$ .

Q: How do I find the value of b?

A: To find the value of $b$ , you need to substitute $x = 1$ into the equation $y = ax^5$ . This will give you the equation $y = a(1)^5 = a = \frac{3}{10}$ . Therefore, the value of $b$ is $\frac{3}{10}$ .

Q: What is the equation of the tangent to the curve at the origin?

A: The equation of the tangent to the curve at the origin is $y = 0$ .

Q: Why is the slope of the tangent line at the origin 0?

A: The slope of the tangent line at the origin is 0 because the derivative of $y = ax^5$ at $x = 0$ is 0.

Q: Can I use the power rule of differentiation to find the derivative of y = ax^5?

A: Yes, you can use the power rule of differentiation to find the derivative of $y = ax^5$ . The power rule states that if $y = x^n$ , then $\frac{dy}{dx} = nx^{n-1}$ . In this case, $n = 5$ , so the derivative of $y = ax^5$ is $\frac{dy}{dx} = 5ax^4$ .

Q: What is the significance of the value of a?

A: The value of $a$ determines the shape of the curve. In this case, the value of $a$ is $\frac{3}{10}$ , which means that the curve is a fifth-degree polynomial.

Q: Can I use the equation of the tangent line to find the value of b?

A: No, you cannot use the equation of the tangent line to find the value of $b$ . The equation of the tangent line is $y = 0$ , which means that the tangent line is a horizontal line that passes through the origin. The value of $b$ is determined by the equation $y = ax^5$ , not by the equation of the tangent line.

Q: What is the relationship between the derivative and the equation of the tangent line?

A: The derivative of a function is related to the equation of the tangent line. The derivative of a function at a point gives the slope of the tangent line at that point. In this case, the derivative of $y = ax^5$ at $x = 0$ is 0, which means that the slope of the tangent line at the origin is 0.

Conclusion

In this article, we have answered some frequently asked questions related to the problem of finding the value of $a$ and $b$ in the equation $y = ax^5$ , given that $\frac{dy}{dx} = \frac{3}{2}$ at $(1, b)$ . We have also discussed the significance of the value of $a$ and the relationship between the derivative and the equation of the tangent line.

References

[1] Calculus, James Stewart, 8th edition, Brooks Cole, 2015.
[2] Differential Calculus, Michael Spivak, Publish or Perish, 2008.

Glossary

Derivative: A measure of how a function changes as its input changes.
Power Rule: A rule for differentiating functions of the form $y = x^n$ .
Tangent Line: A line that just touches a curve at a single point.