Thursday

December 8, 2016
Posted by **lana** on Tuesday, June 16, 2009 at 10:39am.

- calculus -
**Reiny**, Tuesday, June 16, 2009 at 11:02amI assume you meant

y = (2x^4 + 1)(x - 5)

using the product rule

dy/dx = (2x^4+1)(1) + 8x^3(x-5)

simplify and set it equal to 1 gives me

2x^4 + 1 + 8x^4 - 40x^3 = 1

10x^4 - 40x^3 = 0

10x^3(x-4) = 0

so x = 0 or x = 4

those are the x's of your two points where the slope of the tangent is 1

sub into the origianal to get the y's