Power Rule and Product Rule

The power rule is your go-to tool for differentiating polynomials. When you have y = x^n, the derivative is y' = nx^$n-1$. This means you multiply by the exponent and then reduce the exponent by 1. For example, if f$x$ = x^4 + 3x^3 - 7x^2 + 6x - 2, then f'$x$ = 4x^3 + 9x^2 - 14x + 6.

With radicals, convert to fractional exponents first. For f$x$ = ∛x^3, rewrite as x^$3/4$, then apply the power rule to get f'$x$ = $3/4$x^$-1/4$, which can be written as 3/(4∛x).

The product rule handles functions being multiplied together. For y = f × g, the derivative is y' = f'g + fg'. This means you differentiate the first function while keeping the second the same, then add that to the first function times the derivative of the second function.

💡 When finding tangent lines, remember the point-slope form: y - y₁ = m$x - x₁$, where m is the derivative evaluated at the point. This connects calculus to the linear equations you already know!

When calculating tangent lines, first find the y-coordinate by evaluating the function, then find the slope by evaluating the derivative at that point.

Quotient Rule and Chain Rule

The quotient rule handles division between functions. If y = f/g, then y' = $f'g - fg'$/g². This formula might look intimidating, but think of it as: (derivative of top × bottom) minus (top × derivative of bottom), all divided by (bottom squared).

For example, differentiating y = $5x² - 3x + 2$/$4x - 8$ requires applying the quotient rule carefully. The numerator becomes the difference between two products, which you can then simplify.

The chain rule is essential when functions are "nested" inside each other. When y = [f$x$]^n, the derivative is y' = n[f$x$]^$n-1$ × f'$x$. You're essentially differentiating the outer function and multiplying by the derivative of the inner function.

For instance, to find y' for y = $7x² + 9$^4, you'd get y' = 4$7x² + 9$^3 × 14x = 56x$7x² + 9$^3.

💡 Position, velocity, and acceleration are related through derivatives! If f$x$ represents position, then f'$x$ is velocity, and f''$x$ is acceleration. This makes calculus incredibly useful for physics problems.

The chain rule often combines with other rules in complex problems. Being able to recognize when to use each rule will make solving differentiation problems much easier.