Define what it means for a limit to exist at x=a.
The left-hand and right-hand limits both exist and are equal: limx→a−f(x)=limx→a+ f(x)
Simplify (1/(x+h) - 1/x)/h
-1/(x(x+h)
What is sin(0)?
0
State the limit definition of the derivative
f'(x) = limh→0 (f(x+h)-f(x))/h
Define continuity at x=a
f(a) exists, limx→af(x) exists, left and right hand limits are equal
Evaluate limx→3 (x2-9)/((x-3)
6
Simplify limx→4 √(x-2)/(x-4)
1/4
Evaluate limx→0 sin(x)/x
1
Interpret f'(a) graphically
It's the slope of the tangent line at x=a
Determine if f(x) = { x+2, x<1
x2, x≥1
is continuous at x=1
Yes, both sides equal 2
A limit gives 0/0. What does that mean?
It's indeterminate, you must simplify or rationalize before evaluating
Find the derivative of f(x) = 1/x using the limit definition
f'(x) = -1/x2
Evaluate limx→0 (1-cos(x))/x2
1/2
Find f'(x) for f(x) = (x2+3x)/(x+1) using standard derivative rules
(x2+2x+3)/(x+1)2
Find the value of k that makes
f(x) = {x2, x<2
kx-2, x≥2
left and right hand limits must equal
-->4=2k-2
--> k=3
Evaluate limx→0 sin(3x)/x
3
Rationalize the numerator (√(x+1) - √x )/h
1/(√(x+1) + √x )
What is the d/dx sin(x), d/dx cos(x), d/dx tan(x)
cos(x), -sin(x), sec2(x)
Use the limit definition of the derivative to find f'(x) for f(x) = √(x+2)
1/(2√(x+2))
Let f(x) = {x2, x<1
2x, x≥1
Determine whether f(x) is continuous and differentiable at x=1
2. Its left and right derivatives must be equal at x=1
--> left and right hand don't match so not continuous
--> if a fan is not continuous, it can't be differentiable (but let's still check)
f(x)={x2 x<2
3x-2 x≥2
Is f continuous at x=2?
Yes, both sides equal 4
Simplify 1/(1/x + 1/y)
xy/(x+y)
What’s sin(π/6), cos(π/6), and tan(π/6)?
1/2, √3/2, 1/√3
f(x) = 1/(x+1). Find f'(x) using any method, then find the equation of the tangent line at (1,1/2)
f'(x) = -1/(x+1)2
y= (-1/4)x + 3/4
f(x)={ x2, x<1
2x-1, x≥1
1. Is f(x) continuous at x=1?
2. Is f(x) differentiable at x=1?
3. If differentiable, find the equation of the tangent line at (1,1)
y=2x-1