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Find the equation of the normal to the curve 
y=(x-2)/(2x+1) at the point where the curve cuts the 
x-axis.

Find the equation of the normal to the curve y=x22x+1 y=\frac{x-2}{2 x+1} at the point where the curve cuts the x x -axis.

Full solution

Q. Find the equation of the normal to the curve y=x22x+1 y=\frac{x-2}{2 x+1} at the point where the curve cuts the x x -axis.
  1. Find x-intercept: First, we need to find the point where the curve cuts the x-axis. This happens when y=0y=0.\newliney=x22x+1=0y = \frac{x-2}{2x+1} = 0\newlineTo find the x-coordinate of this point, we set the numerator of the fraction to zero because a fraction is zero if and only if its numerator is zero.\newlinex2=0x - 2 = 0\newlinex=2x = 2
  2. Determine point coordinates: Now we have the xx-coordinate of the point where the curve cuts the xx-axis. The yy-coordinate is already known to be 00 since it's on the xx-axis. So the point is (2,0)(2, 0).
  3. Calculate tangent slope: Next, we need to find the slope of the tangent to the curve at the point (2,0)(2, 0). To do this, we find the derivative of yy with respect to xx.y=x22x+1y = \frac{x-2}{2x+1}Using the quotient rule, the derivative yy' is:y=(2x+1)(1)(x2)(2)(2x+1)2y' = \frac{(2x+1)(1) - (x-2)(2)}{(2x+1)^2}y=2x+12x+4(2x+1)2y' = \frac{2x+1 - 2x + 4}{(2x+1)^2}y=5(2x+1)2y' = \frac{5}{(2x+1)^2}
  4. Evaluate slope at x=2x=2: Now we evaluate the derivative at the point x=2x=2 to find the slope of the tangent.\newliney(2)=5(22+1)2y'(2) = \frac{5}{(2\cdot2+1)^2}\newliney(2)=5(4+1)2y'(2) = \frac{5}{(4+1)^2}\newliney(2)=525y'(2) = \frac{5}{25}\newliney(2)=15y'(2) = \frac{1}{5}
  5. Find normal slope: The slope of the normal is the negative reciprocal of the slope of the tangent. Since the slope of the tangent at x=2x=2 is 15\frac{1}{5}, the slope of the normal is 5-5.
  6. Derive normal equation: Now we have the slope of the normal and a point through which it passes. We can use the point-slope form of the equation of a line to find the equation of the normal.\newlineThe point-slope form is: yy1=m(xx1)y - y_1 = m(x - x_1), where mm is the slope and (x1,y1)(x_1, y_1) is the point.\newlineUsing the point (2,0)(2, 0) and the slope 5-5, the equation is:\newliney0=5(x2)y - 0 = -5(x - 2)\newliney=5x+10y = -5x + 10

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