Determine the equation of both lines that are tangent to the graph of y=x^2 +4 and pass through the point (1,-2) So would I simply use the y=mx+b form, m=2, y= -2, and x = 1?
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Originally Posted by RyGuy Determine the equation of both lines that are tangent to the graph of y=x^2 +4 and pass through the point (1,-2) So would I simply use the y=mx+b form, m=2, y= -2, and x = 1? no ... the point (1,-2) does not lie on the parabola.
Originally Posted by skeeter no ... the point (1,-2) does not lie on the parabola. Oh right. So then how would I go about this?
Originally Posted by RyGuy Determine the equation of both lines that are tangent to the graph of y=x^2 +4 and pass through the point (1,-2) So would I simply use the y=mx+b form, m=2, y= -2, and x = 1? the derivative of the parabola equation gives the slope of all tangent lines to the curve. You need the equations of the two that pass through (1,-2). hence, write the derivative to get the slopes of these lines. then use
point of tangency on the curve is each tangent line passes thru the point remember how to find the slope between two points? ... also, note that the slope of both tangent lines is y' = 2x I'll let you take it from here.
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