How do you find the equation of the tangent line to the graph #y=2^-x# through point (-1,2)?
Use logarithmic differentiation.
Evaluate the derivative at
Use the point-slope form of the equation of the line.
Use the natural logarithm on both sides of the equation:
Use the property
Differentiate both sides:
Multiply both sides by y:
Substitute for y:
The slope, m, of the tangent line is the derivative evaluated at
Using the point-slope form of the equation of the line: