Ideas in Geometry/Instructive examples/Section 1.2 problem

y=x^20-23x+4 at point x=0 f(x)=x^20-23x+4 f(x) is the slope of tangent line of this equation f(x)=20x^19-23 through calculus we that f(x)=x^a+....... (f^/)(x)=(a(x)^a-1)+...... f^/(x)is the slope of f(x) that is proven

f(x)=20x^19-23 at x=0 f(x)=(20(0)^19)-23 f(x)=-23 means the slope is -23 at x=0 y=0^20-23(0)+4   y=4

y=mx+b tangent line equation y=4 m=-23 x=0 4=-23(0)+b  4=b

so the equation is...... y=-23x+4 of the tangent line