Finding Velocity Zero: Solving a High School Calculus Problem

[undrcvrbro]

[SOLVED] high school calc problem

Homework Statement

If an object moves along the y-axis (marked in feet) so that its position at time x (in seconds) is given by the indicated function; y= (x^3)-(9x^2)+15x;
Find when v=0

Homework Equations

v=y prime, and i already have found y prime to be (3x^2)-(18x)+15

The Attempt at a Solution

I checked the selected answers in the back of the book and did a little plug and chug and called it a day..... haha. I'm assuming there's a more relevant process so any help is mucho appreciated. thanks.

 

[rock.freak667]

if v=y'

then shouldn't $v=3x^2-18x+15$

when v=0

$3x^2-18x+15=0$


try some factorisation

 

[undrcvrbro]

wow...thank you

haha I am not sure how i didn't see that. I really didn't think anyone would answer. I believe I've just found a new home for homework help...and considering I will be going into chemE next next year in college, I should be revisiting many of times!

haha thank you a lot!