Calculus Related Rates Problem: Given an equation, find the rate. Not all Related Rates problems are word problems. Here’s a different type that came from a student. The problem gives you an equation, and then asks you to find a rate: If $y = x^3 + 2x$ and $\dfrac{dx}{dt} = 6$, find $\dfrac{dy}{dt}$ when $x=5.$… [read more]

Calculus Related Rates Problem: As a snowball melts, its area decreases at a given rate. How fast does its radius change? A spherical snowball melts symmetrically such that it is always a sphere. Its surface area decreases at the rate of $\pi$ in$^2$/min. How fast is its radius changing at the instant when $r =… [read more]

Calculus Related Rates Problem: Lamp post casts a shadow of a man walking. A 1.8-meter tall man walks away from a 6.0-meter lamp post at the rate of 1.5 m/s. The light at the top of the post casts a shadow in front of the man. How fast is the “head” of his shadow moving… [read more]

Evaluating Limits: Problems and Solutions You probably already understand the basics of what limits are, and how to find one by looking at the graph of a function. So we’re going to jump right into where most students initially have some trouble: how to actually evaluate or compute a limit in homework and exam problems,… [read more]

Need to solve Optimization problems in Calculus? Let’s break ’em down and develop a strategy that you can use to solve them routinely for yourself. Overview Optimization problems will always ask you to maximize or minimize some quantity, having described the situation using words (instead of immediately giving you a function to max/minimize). Typical phrases… [read more]

Calculus Optimization Problem: What dimensions minimize the cost of a garden fence? Sam wants to build a garden fence to protect a rectangular 400 square-foot planting area. His next-door neighbor agrees to pay for half of the fence that borders her property; Sam will pay the rest of the cost. What are the dimensions of… [read more]

Calculus Optimization Problem Solving Strategy We will use the steps outlined below to solve each Calculus Optimization problem on this site, step-by-step, every single time. We hope that this will help you see the strategy we’re using so you can learn it too, and then be able to apply it to all of your problems,… [read more]

Calculus Optimization Problem: What are the dimensions of the poster with the smallest total area? A rectangular poster must have a printed area of 320 cm$^2$. It will have top and bottom margins that are 5 cm each, and side margins that are 4 cm. What are the dimensions of the poster with the smallest… [read more]

Calculus Optimization Problem: What dimensions minimize the cost of an open-topped can? An open-topped cylindrical can must contain V cm$^3$ of liquid. (A typical can of soda, for example, has V = 355 cm$^3$.) What dimensions will minimize the cost of metal to construct the can? Calculus Solution We’ll use our standard Optimization Problem Solving… [read more]

Optimization: Problems and Solutions We will solve every Calculus Optimization problem using the same Problem Solving Strategy time and again. You can see an overview of that strategy here (link will open in a new tab). We use that strategy to solve the problems below. Want access to all of our Calculus problems and solutions?… [read more]