Calculus HL

[Hrishi98]

Guys, I need a little help in this question,

 

The curve y=f(x) that passes through the origin. Given the f '(x)= 3x^2-8x-5. Find the coordinates of the other points where the curve crosses the x-axis.

Could you help, cause im completely off ideas on this one

 

[Guest SNJERIN]

Just take its integral and you would get the following:

 

y=f(x) = x^3 - 4x^2 - 5x + C but since the curve passes the origin C would be zero

 

Now:

 

y= x(x-5)(x+1 ) hence the roots are 5 , -1 thus the coordinates will be P(5,0) and Q(-1,0) 

[Hrishi98]

Just take its integral and you would get the following:

 

y=f(x) = x^3 - 4x^2 - 5x + C but since the curve passes the origin C would be zero

 

Now:

 

y= x(x-5)(x+1 ) hence the roots are 5 , -1 thus the coordinates will be P(5,0) and Q(-1,0) 

Thanks man, I was stuck after the integral step. I didn't know the constant would be zero, but yeah appreciate the assist by the way.