Determine the equations of both lines that are tangent to the graph of f(x)=x^2 and pass through point (1,-3).

Question

anonymous · Answer

I got the slope: m=2

anonymous · Answer

(1, -3) is not a point on the graph..

phi · Answer

tangent to the graph of f(x)=x^2
means  one point on the line is also on this curve, at (x, x^2)
because y= x^2

the slope of the tangent line will be  2x (take the derivative of x^2)
use  the point slope formula through point (1,-3)
y - (-3) = m ( x - 1)
slope is 2x,  y is x^2
x^2 +3 = 2x(x-1)
simplify and solve for x (2 values) 

now you have two points:   (1,-3)  and (x,x^2)  (evaluated at the correct x)
from which you can find an equation of the tangent line

anonymous · Answer

aahh.. got it thanks a lot!!!(^_^)