Posted by **Allison** on Thursday, September 29, 2011 at 1:07pm.

For what values of x is the tangent line of the graph of

f(x)=8x3+36x2+46x−72

parallel to the line y=−2x+1.9 ? Enter the x values in order, smallest first, to 4 places of accuracy:

x1= ≤ x2=

- Calculus -
**Steve**, Thursday, September 29, 2011 at 3:00pm
f(x) = 8x³ + 36x² + 46x - 72

f'(x) = 24x² + 72x + 46

The slope of y = -2x+1.9 is -2

So, we want to find values of x where f'(x) = -2

24x² + 72x + 46 = -2

24x^2 + 72x + 48 = 0

x^2 + 3x + 2 = 0

(x+1)(x+2)

So, x = -2.0000, -1.0000

## Answer This Question

## Related Questions

- Calculus - If f(x)=[(x−1)/(1+5x)], there are two points on the graph of y=...
- Calculus - If f(x)=[x−1/(1+5 x)], there are two points on the graph of y=f...
- calculus - f(t) = − 4 t2 − t− 6 Find the equation of the line...
- Maths-Calculus - If f(2)=1 and f(2+h)=(h+1)3, compute f′(2). If f(−...
- calculus - please anyone help me out Consider the following. Function Point f(x...
- Math - The point P(8, −3) lies on the curve y = 3/(7 − x). (a) If Q ...
- calculus - Write the equation of the tangent line to the curve at the indicated ...
- Calculus - Sketch a graph of the parabola y=x^2+3. On the same graph, plot the ...
- Calculus - Let f(x)=21−x^2 The slope of the tangent line to the graph of f...
- Calculus - 1. On what interval is the function f(x)=x^3-4x^2+5x concave upward? ...

More Related Questions