[tex]f(x)=2x^3-4x[/tex]
take the derivitive to find the slope
[tex]f'(x)=3*(2x^2)-2*(4x^0)[/tex]
[tex]f'(x)=6x^2-4[/tex]
so at x=1, the slope is f'(1)=6(1)^2-4=6-4=2
y=mx+b
y=2x+b
find b
at x=1, f(1)=2(1)^3-4(1)=2-4=-2=y
-2=2(1)+b
-2=2+b
-4=b
equation is y=2x-4
