Sunday

September 21, 2014

September 21, 2014

Posted by **Ronnie** on Saturday, June 19, 2010 at 1:06pm.

Let f(x)= (2x-9)(x^2 + 6)

(A) Find the equation of the line tangent to the graph of f(x) at x=3

(B) Find the values(s) of x where the tangent line is horizontal.

- College Math -
**Reiny**, Saturday, June 19, 2010 at 5:11pmI would expand the function first, then find the derivative.

f(x) = 2x^3 + 12x - 9x^2 - 54

f '(x) = 6x^2 + 12 - 18x

when x = 3

f(3) = -3(15) = -45

f '(3) = 6(9) + 12 - 18(3) = 12

A) so you have a slope of 12 and a point (3,-45)

Use y = mx + b to find the tangent equation

B) set 6x^2 - 18x + 12 = 0

and solve

Hint: divide both sides by 6, then it factors

- College Math -
**Anonymous**, Friday, June 25, 2010 at 4:58pmIdentify the variable, constant, and coefficient of the expression: –10k + 15

**Answer this Question**

**Related Questions**

math help - Thank you for helping me with the last problem Reiny and Bosnian. ...

Math - 3x-4 to y+15 is constant and y=3 when x=2 then when y=12, x equals? My ...

Math - 1. What are the steps to solve this problem? 0.000027 ÷ 0.000009 ...

Geometry :( - this maths problem is wrecking my head.... 1.find the points of ...

Math - 1. What are the steps to solve this problem? 0.000027 ÷ 0.000009 • ...

College Math II - a^4 - ab^3 = I have asked this question on many web sites and...

Child development - Using these steps, consider a cognitive “problem” a young ...

algebra 1 - Can someone please help me with this inequality problem -3-8>(4x+...

College Math II - x/x – 1 - 3/x = 1/4 My problem says to show the work and to ...

Math - Please help I have the answer to the problem but can figure the steps to ...