All Calculus 1 Resources
Example Questions
Example Question #191 : Differential Functions
What is the first derivative of s(x) = 2sin(sin(x))?
ln(2) * 2sin(sin(x)) * cos(sin(x)) * cos(x)
None of the other answers
2cos(x)sin(x)
2cos(sin(x)) * cos(x)
ln(2) * 2cos(sin(x)) * cos(x)
ln(2) * 2sin(sin(x)) * cos(sin(x)) * cos(x)
We must carefully parse this function in order to apply the chain rule correctly. Let us make the following substitutions:
f(x) = 2x
g(x) = sin(sin(x))
s(x) = f(g(x)) = 2sin(sin(x))
According to the chain rule, we know that s'(x) = f'(g(x)) * g'(x)
f'(g(x)) = ln(2) * 2sin(sin(x))
g'(x) = cos(sin(x)) * cos(x)
Therefore, s'(x) = ln(2) * 2sin(sin(x)) * cos(sin(x)) * cos(x)
Example Question #1 : Other Differential Functions
What is the first derivative of f(x) = sin2(x) – sin(x)cos(x)?
2sin(x)cos(x) – 1
sin2(x) – 2sin(x)cos(x) – cos2(x)
2sin(x)cos(x) + 1
2sin(x)cos(x) + cos2(x) + sin2(x)
2sin(x)cos(x) – cos2(x) + sin2(x)
2sin(x)cos(x) – cos2(x) + sin2(x)
Consider each of the elements in isolation:
sin2(x) can be differentiated using the chain rule.
Step 1: 2(sin(x))
Step 2: take the derivative of sin(x): cos(x)
Therefore, d/dx (sin2(x)) = 2sin(x)cos(x)
sin(x)cos(x) can be differentiated by the product rule:
cos(x)cos(x) + sin(x) * –sin(x) = cos2(x) – sin2(x)
Combine these:
2sin(x)cos(x) – (cos2(x) – sin2(x)) = 2sin(x)cos(x) – cos2(x) + sin2(x)
Example Question #2 : How To Find Differential Functions
What is the first derivative of f(x) = sin(x)ln(cos(x))?
cos(x)ln(cos(x)) + tan(x)sin(x)
cos(x)ln(cos(x)) – tan(x)sin(x)
None of the other answers
cos(x)ln(sin(x)) – sin2(x)
cos(x)ln(cos(x)) – tan(x)csc(x)
cos(x)ln(cos(x)) – tan(x)sin(x)
This is a mixture of the product rule and the chain rule:
The first term of the product rule is: cos(x)ln(cos(x))
The second term will have sin(x) but will include the differentiation of the ln(cos(x)), which will require the chain rule:
sin(x) * (1/cos(x)) * (–sin(x)) = –sin2(x)/cos(x)
Combining both we get:
cos(x)ln(cos(x)) – sin2(x)/cos(x)
Now, note that none of the answers are the same as this ;however, we can make an alteration:
sin(x)/cos(x) is the same as tan(x)
Therefore, the answer is: cos(x)ln(cos(x)) – tan(x)sin(x)
Example Question #2 : Other Differential Functions
What is the first derivative of f(x) = sin(cos(tan(sin(x))))
sin(sin(tan(sin(x)))) * tan(sin(x))cos(x) * sin(sec2(sin(x)))
–cos(cos(tan(sin(x)))) * sec2(sin(x))cos(x) * sin(tan(sin(x)))
None of the other answers
cos(cos(tan(sin(x))))) * cos(tan(sin(x)))
cos(cos(tan(sin(x))))
–cos(cos(tan(sin(x)))) * sec2(sin(x))cos(x) * sin(tan(sin(x)))
Okay, don't be overwhelmed. Take this chain rule one step at a time:
Step 1: Do the sine...
cos(cos(tan(sin(x))))
Step 2: Do the cosine . . .
–sin(tan(sin(x)))
Step 3: do the tangent . . . this is the simple chain rule, so diffentiate the argument as well
sec2(sin(x))cos(x)
Step 4: Multiply them together:
–cos(cos(tan(sin(x)))) * sec2(sin(x))cos(x) * sin(tan(sin(x)))
Example Question #3 : How To Find Differential Functions
What is the first derivative of f(x) = sec(x2 + 4x)?
sec(2x + 4)tan(2x + 4)
2x * sec(x2 + 4x)tan(x2 + 4x) + 4sec(x2 + 4x)tan(x2 + 4x)
2x * tan(x2 + 4x) + 4tan(x2 + 4x)
2x * tan2(x2 + 4x) + 4tan2(x2 + 4x)
sec(x2 + 4x)tan(x2 + 4x)
2x * sec(x2 + 4x)tan(x2 + 4x) + 4sec(x2 + 4x)tan(x2 + 4x)
This is a simple chain rule. The derivative of the secant is secant * tangent; therefore:
f'(x) = sec(x2 + 4x) * tan(x2 + 4x) * (2x + 4)
Distribute everything to get your answer: 2x * sec(x2 + 4x)tan(x2 + 4x) + 4sec(x2 + 4x)tan(x2 + 4x)
Example Question #4 : Other Differential Functions
What is the first derivative of f(x) = cos4(x2)
–8x * sin(x2)cos3(x2)
4cos3(x2)
4cos3(x2)sin(x2)
4x * cos3(x2)
4x * sin(x2)cos3(x2)
–8x * sin(x2)cos3(x2)
Consider this as a chain rule case. Do each step:
Step 1: cos4
4cos3(x2)
Step 2: cos(x2); this can be treated like a normal case of the chain rule
–sin(x2) * 2x
Combining these, we get
–8x * sin(x2)cos3(x2)
Example Question #5 : Other Differential Functions
What is the first derivative of f(x) = (100/x2) + (50/x) – 200x2?
(14 + 4x + 3x4)/x3
(50 + 50x – 400x2)/x
–50(4 + x + 8x4)/x3
200x + 50 – 400x
None of the other answers
–50(4 + x + 8x4)/x3
f(x) = (100/x2) + (50/x) – 200x2
First, rewrite the equation: 100x–2 + 50x–1 – 200x2
At this point, it is relatively easy to differentiate:
f'(x) = –2 * 100x–3 – 50x–2 – 400x = (–200/x3) – (50/x2) – 400x
Simplify by making x3 the common denominator:
(–200 – 50x – 400x4)/x3
Factor out the common –50 in the numerator to make things look nicer:
–50(4 + x + 8x4)/x3
Example Question #192 : Differential Functions
What is the first derivative of f(x) = 2x * ln(sin(x))?
2(ln(sin(x)) + x * tan(x))
2(ln(sin(x)) + x * cot(x))
2ln(sin(x))/cos(x)
2tan(x)
None of the other answers
2(ln(sin(x)) + x * cot(x))
f(x) = 2x * ln(sin(x))
Here, we have a product rule with a chain rule.
The derivative of ln(sin(x)) = (1/sin(x)) * cos(x). Note that this is cot(x).
Therefore, our full derivative is:
f'(x) = 2ln(sin(x)) + 2x * cot(x) = 2(ln(sin(x)) + x * cot(x))
Example Question #12 : Other Differential Functions
What is the first derivative of f(x) = sin4(x) – cos3(x)?
4sin3(x) + 3cos2(x)
sin4(x)cos(x) + cos3(x)sin(x)
sin(x) + 1
4sin3(x)cos(x) + 3cos2(x)sin(x)
4sin3(x)cos(x) – 3cos2(x)sin(x)
4sin3(x)cos(x) + 3cos2(x)sin(x)
f(x) = sin4(x) – cos3(x)?
Treat these as chain rules:
The derivative of sin4(x) is therefore: 4sin3(x)cos(x)
The derivative of cos3(x) is therefore: 3cos2(x) * –sin(x) or –3cos2(x)sin(x)
This gives us 4sin3(x)cos(x) + 3cos2(x)sin(x), which really cannot be simplified any further.
Example Question #13 : Other Differential Functions
What is the the first derivative of f(x) = 2tan(x)?
cot(x) * ln(2) * 2tan(x)
sec2(x) * ln(2) * 2tan(x)
ln(2) * 2sec(x)tan(x)
ln(2) * 2tan(x)
sec(x) * tan(x) * ln(2) * 2tan(x)
sec2(x) * ln(2) * 2tan(x)
This is a case of the chain rule.
Step 1: Deal with the exponential function
ln(2) * 2tan(x)
Step 2: Deal with the exponent
sec2(x)
Multiply them together to get your answer:
sec2(x) * ln(2) * 2tan(x)