Posted by David on Thursday, April 1, 2010 at 11:03pm.
4. For the curve with y = 2x3 + x  6, find:
(b.) the gradient at the point (1, 5)
(c.) the equation of the tangent line at the point (1, 5).

math  Reiny, Thursday, April 1, 2010 at 11:18pm
y = 2x^3 + x  6
dy/dx = 6x + 1
at (1,5), dy/dx = 6(1) + 1 = 7
so y = 7x + b
at (1,5)
5 = 7(1) + b
b = 12
equation of tangent is y = 7x  12 
math  Hi, Tuesday, April 6, 2010 at 7:59pm
y = 2x^3 + x  6
dy/dx = 6x + 1
at (1,5), dy/dx = 6(1) + 1 = 7
so y = 7x + b
at (1,5)
5 = 7(1) + b
b = 12
equation of tangent is y = 7x  12