
Calculus Calculus Math Forum 
 LinkBack  Thread Tools  Display Modes 
October 31st, 2017, 07:57 PM  #1 
Newbie Joined: Oct 2017 From: California Posts: 2 Thanks: 0  Please help me gradient of tangent
f(x)=ax^2+c dy/dx=2ax Point A (2,5) lies on the graph of y=f(x). the gradient of the tangent to this graph at A is 6. Find the value of a and c. 
October 31st, 2017, 08:09 PM  #2 
Global Moderator Joined: Oct 2008 From: London, Ontario, Canada  The Forest City Posts: 7,900 Thanks: 1094 Math Focus: Elementary mathematics and beyond 
Where are you having difficulty? The problem can be solved by straightforward substitution. $$f'(2)=2a(2) = 6$$ Can you continue? 
October 31st, 2017, 08:11 PM  #3 
Newbie Joined: Oct 2017 From: California Posts: 2 Thanks: 0 
can you please finish it? I am not sure why, but I am so confused on finding both a and c. I have been doing math all day

November 2nd, 2017, 04:41 AM  #4 
Math Team Joined: Jan 2015 From: Alabama Posts: 3,261 Thanks: 895  Since "(2, 5) lies on the graph", f(2)= a(4)+ c= 5. The "gradient of the tangent" is 2a= 6. Find a then put that value into the first equation and find c.


Tags 
gradient, tangent 
Thread Tools  
Display Modes  

Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Gradient and Hessian  dhhtr  Differential Equations  0  May 11th, 2015 01:04 AM 
gradient of y= 2x +8 ??  coachcft  Calculus  2  December 15th, 2012 01:25 PM 
Gradient  truthseeker  Linear Algebra  12  October 2nd, 2012 08:07 AM 
Gradient  veronicak5678  Real Analysis  0  May 6th, 2012 10:08 AM 
Is it possible to replace in a term tangent by arc tangent?  me  Trigonometry  3  January 31st, 2008 10:30 AM 