Graphing Tangents to a Quadratic Curve

In summary, the task is to find an equation for the tangent to the curve y=3-x^2 at the point (-1,2) and sketch the curve and tangent together. Using the formula for slope, we find the slope to be 2. Then using the point-slope formula, we get the equation for the tangent to be y=2x+4. To graph the tangent, we can plot the point (-1,2) and use the slope to find additional points on the line. To find where the tangent crosses the x-axis, we can set y=0 in the equation y=2x+4 and solve for x.
  • #1
pooker
16
0

Homework Statement


Find an equation for the tangent to the curve at the given point. Then sketch the curve and tangent together

Homework Equations


y=3-x^2 (-1,2)

The Attempt at a Solution



slope =

f(x + h) + f(x) / h

f(-1 + h) + 2 / h

3- (-x + h)^2 + 2 / h

3 - 1 + 2h + H^2 + 2 / h

2h + h^2 / h

= 2 + h
= 2

slope is 2

y - y1 = m(x - x1)

y - 2 = 2 (x + 1)
y = 2x + 4 = equation Ok so I have no idea how to graph a tangent, can someone tell me how you graph this? I know how to sketch the graph 3- x^2 since it is a ^2 function it is u shaped, flipped on the x-axis moved up three on the y. I know the tangent obviously passes through -1, 2 but how do I graph the rest? I know y intercept for tangent is 4, but where does it pass through x at? I am a little rusty
 
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  • #2
Do you mean where does it cross the x-axis? It does that when y=0 in the equation y=2x+4. Solve for x. You are rusty. It's just graphing a straight line.
 

1. What is the slope of a tangent line?

The slope of a tangent line is the instantaneous rate of change at a specific point on a curve. It represents the steepness of the curve at that point.

2. How do you graph the slope of a tangent line?

To graph the slope of a tangent line, you first need to find the slope at a specific point on the curve by taking the derivative at that point. Then, you can plot the point on the curve and draw a line with the calculated slope passing through that point.

3. What is the difference between average slope and slope of a tangent line?

The average slope measures the overall change in a curve over a given interval, while the slope of a tangent line measures the instantaneous change at a specific point on the curve.

4. Can the slope of a tangent line be negative?

Yes, the slope of a tangent line can be positive, negative, or zero. It depends on the shape of the curve at the specific point where the tangent line is drawn.

5. How is the slope of a tangent line used in real life?

The slope of a tangent line is used in various fields of science, such as physics, engineering, and economics, to calculate rates of change and predict future trends. It is also used in calculus to find maximum and minimum values of functions.

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