Question

Show that the curve y=10x^3+4x+2 has no tangent lines with slope 3.

Answer 1

HI!!

Answer 2

take the derivative, you will get a quadratic

Answer 3

set it equal to 3 and try to solve
no doubt you will get no solution, i.e. a discriminant that is negative

Answer 4

how do you take a derivative? @misty1212

Answer 5

i got 0=30x^2+1

Answer 6

Derivative should be 30x^2+4 (because your x has a coefficient of 4)

Answer 7

oh i set it to equal to 3

Answer 8

do you not know how to find the derivative of a polynomial?

Answer 9

i think so, it will be y'= 30x^2+4

Answer 10

\[30x^2+4=3\\
30x^2=-1\] no real solution

Answer 11

oh i see thanks!