If r > 0 is a national number (integer/integer) then the limit
Lim as a goes to infinity 1/x^r =0
If r > 0 is a rational number such that x^r is defined for all x then the limit
Lim as x goes to negative infinity 1/x^r =0
Equation of a tangent line
y - y0 = m(x- x0)
Derivative of a function
f’(x) = lim h —> 0 ( f(x+h) - f(x) / (h))
Infinity is
NOT a number, you may not do arithmetic with it
Lim as a approaches infinity f(x) = x^3
Infinity (it increases quickly)
Lim as x approaches negative infinity f(x) = 1/x
Zero ( it gets smaller and smaller)
Lim as x approaches infinity f(x) = cos(x)
DNE (oscillates too much)
How to evaluate limits at infinity
If p(x) and q(x) are polynomials, then to evaluate Lim as a goes to positive/negative infinity p(x)/q(x), we divide the numerator and denominator by the highest power of x in the denominator
Horizontal Asymptote
Line y=L of y=f(x) is a horizontal asymptote if either Lim as x approaches infinity = L or Lim as x approaches negative infinity = L
Average rate of change
Slope of secant line through the points (a, f(a)) and (b,f(b))
Instantaneous rate of change
Slope of tangent line through one point (a,f(a))
Derivative of a function at x=a
f'(a)= lim as h approaches 0 ((f(a+h) - f(a)) / h)
Derivative at a point x=a
Instantaneous rate of change, slope of the tangent line at x=a
The derivative is the slope of a tangent line at a point
f(x) horizontal slope = 0
f'(x) intersects at 0
f(x) positive to negative
f’(x) minimum point
f(x) negative to positive
f’(x) maximum point
f(x) negative/decreasing slope
f’(x) line is below the x-axis (negative)
f(x) positive/increasing slope
f’(x) is above the x-axis (positive)
When the function f(x) is increasing
the derivative f’(x) must be positive
When the function f(x) is decreasing
The derivative f’(x) must be negative
The function f(x) is NOT differentiable when there are
holes (DNE)
corners ( not approaching the same value)
Cusps ( going to infinity)
Vertical lines
Jump discontinuities
If a function is differentiable at x=a
it is continuous
If a function is continuous at x=a
it is NOT necessarily differentiable
First Derivative
f’(x) = y’ = dy/dx = d/dx(f(x))
Second Derivative
f’’(x) = y’’ = d^2y/dx^2 = d^2/dx^2 (f(x))
f(x), f’(x), f’’(x)
Position, Velocity, Acceleration
If r > 0 is a national number (integer/integer) then the limit
Lim as a goes to infinity 1/x^r =0
If r > 0 is a rational number such that x^r is defined for all x then the limit