Derivative Calculator

Derivative of $\arccos\left(2\,x\right)$

Differentiated with respect to x. Edit the function · Differentiation rules

Step-by-step solution

Input function
$$\arccos\left(2\,x\right)$$
Start of the differentiation
$$\frac{d}{dx}{\left[\arccos\left(2\,x\right)\right]}$$

Yellow: the expression being replaced. Green: its replacement.

Step 1 — Derivative of Arccosine Differentiation rule
📖 Rule
$$\frac{d}{dx}\arccos\left(u\right)=-\frac{1}{\sqrt{1 - u^{2}}}\cdot u'$$
With:
  • $u = 2\,x$

Why: Differentiate the outer function while keeping its inner argument u. Multiply by u' and evaluate that inner derivative in its own step.

How does this rule work? Wikipedia
🧮 Current expression
$$\bbox[#fff1b8, padding:0.15em]{{\color{black}{\vphantom{\dfrac{d}{dx}}\,\frac{d}{dx}{\left[\arccos\left(2\,x\right)\right]}\,}}}$$
✨ After: Derivative of Arccosine
$$\bbox[#d6f5df, padding:0.15em]{{\color{black}{\vphantom{\dfrac{d}{dx}}\,-\frac{1}{\sqrt{1 - \left(2\,x\right)^{2}}}\,\frac{d}{dx}{\left[2\,x\right]}\,}}}$$
Step 2 — Power of a product Simplification
📖 Rule
$$(a\cdot b)^n=a^n\cdot b^n$$

Why: Every factor of the product is raised to the exponent.

Changed part: $\left(2\,x\right)^{2} \;\Longrightarrow\; 2^{2}\,x^{2}$
🧮 Current expression
$$-\frac{1}{\sqrt{1 - \bbox[#fff1b8, padding:0.15em]{{\color{black}{\vphantom{\dfrac{d}{dx}}\,\left(2\,x\right)^{2}\,}}}}}\,\frac{d}{dx}{\left[2\,x\right]}$$
✨ After: Power of a product
$$-\frac{1}{\sqrt{1 - \bbox[#d6f5df, padding:0.15em]{{\color{black}{\vphantom{\dfrac{d}{dx}}\,2^{2}\,x^{2}\,}}}}}\,\frac{d}{dx}{\left[2\,x\right]}$$
Step 3 — Evaluate numbers Simplification
📖 Rule

Why: Evaluate only the highlighted numeric expression, preserving exact fractions and decimals.

Changed part: $2^{2} \;\Longrightarrow\; 4$
🧮 Current expression
$$-\frac{1}{\sqrt{1 - \bbox[#fff1b8, padding:0.15em]{{\color{black}{\vphantom{\dfrac{d}{dx}}\,2^{2}\,}}}\,x^{2}}}\,\frac{d}{dx}{\left[2\,x\right]}$$
✨ After: Evaluate numbers
$$-\frac{1}{\sqrt{1 - \bbox[#d6f5df, padding:0.15em]{{\color{black}{\vphantom{\dfrac{d}{dx}}\,4\,}}}\,x^{2}}}\,\frac{d}{dx}{\left[2\,x\right]}$$
Step 4 — Constant Factor Rule Differentiation rule
📖 Rule
$$\frac{d}{dx}(c\,u)=c\,u'$$
With:
  • $c = 2$
  • $u = x$

Why: Keep the constant multiplier outside the derivative. Next, differentiate only the part depending on x.

Changed part: $\frac{d}{dx}{\left[2\,x\right]} \;\Longrightarrow\; 2\,\frac{d}{dx}{\left[x\right]}$
How does this rule work? Wikipedia
🧮 Current expression
$$-\frac{1}{\sqrt{1 - 4\,x^{2}}}\,\bbox[#fff1b8, padding:0.15em]{{\color{black}{\vphantom{\dfrac{d}{dx}}\,\frac{d}{dx}{\left[2\,x\right]}\,}}}$$
✨ After: Constant Factor Rule
$$-\frac{1}{\sqrt{1 - 4\,x^{2}}} \cdot \bbox[#d6f5df, padding:0.15em]{{\color{black}{\vphantom{\dfrac{d}{dx}}\,2\,\frac{d}{dx}{\left[x\right]}\,}}}$$
Step 5 — Derivative of a Variable Differentiation rule
📖 Rule
$$\frac{d}{dx}(x)=1$$

Why: When x increases by one, the value of this term also increases by one. Its derivative is therefore one.

Changed part: $\frac{d}{dx}{\left[x\right]} \;\Longrightarrow\; 1$
How does this rule work?
🧮 Current expression
$$-\frac{1}{\sqrt{1 - 4\,x^{2}}} \cdot 2\,\bbox[#fff1b8, padding:0.15em]{{\color{black}{\vphantom{\dfrac{d}{dx}}\,\frac{d}{dx}{\left[x\right]}\,}}}$$
✨ After: Derivative of a Variable
$$-\frac{1}{\sqrt{1 - 4\,x^{2}}} \cdot 2 \cdot \bbox[#d6f5df, padding:0.15em]{{\color{black}{\vphantom{\dfrac{d}{dx}}\,1\,}}}$$
Step 6 — Remove a factor of one Simplification
📖 Rule
$$1\cdot a=a,\quad \frac{a}{1}=a$$

Why: Multiplication or division by one leaves the value unchanged.

Changed part: $2 \cdot 1 \;\Longrightarrow\; 2$
🧮 Current expression
$$-\frac{1}{\sqrt{1 - 4\,x^{2}}} \cdot \bbox[#fff1b8, padding:0.15em]{{\color{black}{\vphantom{\dfrac{d}{dx}}\,2 \cdot 1\,}}}$$
✨ After: Remove a factor of one
$$-\frac{1}{\sqrt{1 - 4\,x^{2}}} \cdot \bbox[#d6f5df, padding:0.15em]{{\color{black}{\vphantom{\dfrac{d}{dx}}\,2\,}}}$$
Step 7 — Combine into one fraction Simplification
📖 Rule
$$a\cdot\frac{b}{c}=\frac{a\cdot b}{c}$$

Why: A factor in front of a fraction multiplies its numerator, giving a single fraction.

🧮 Current expression
$$\bbox[#fff1b8, padding:0.15em]{{\color{black}{\vphantom{\dfrac{d}{dx}}\,-\frac{1}{\sqrt{1 - 4\,x^{2}}} \cdot 2\,}}}$$
✨ After: Combine into one fraction
$$\bbox[#d6f5df, padding:0.15em]{{\color{black}{\vphantom{\dfrac{d}{dx}}\,-\frac{2}{\sqrt{1 - 4\,x^{2}}}\,}}}$$
Final result
$$-\frac{2}{\sqrt{1 - 4\,x^{2}}}$$
Valid where:
  • $-1<2\,x<1$ – The derivative formula is applied in the interior of its real domain.

The derivative is only valid where the original function is defined.

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Cross-check with a computer algebra system

The derivative computed directly by the computer algebra system Maxima:

$$-\frac{2}{\sqrt{1 - 4\,x^{2}}}$$
Step-by-step result ↔ Maxima: identical ✓