Question 330494
Q : tangent to the curve given by
y= x^3 - 5x + 15
at the point where x= -1 ? 


y(-1)=-1+5+15=19
y'(x)=3*x^2-5, y'(-1)=3-5=-2

let ytan(x)=ax+b

ytan(-1)=-a+b=19
ytan'(-1)=a=-2   => b=19+a=17

hence ytan(x)=-2x+17