When Does the Particle Pass Through the Origin?

[anzgurl]

5 A particle moves horizontally in a straight line according to the rule
x(t) = t^3 − 5t^2 + 3t − 5, 0 ≤ t ≤ 7
where x metres is its displacement to the right of the origin at time t seconds.
a What is the initial position of the particle?
b After how many seconds does the particle pass through the origin, correct to 2 decimal
places?

i need help on part b. could some one help me please?
thank you

 

[danago]

When it passes the origin, the displacement is 0 right? Therefore, you could say that x(t)=0 when it passes the origin. So just find the root of the equation that suits the given domain.