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Question

Question: $3t^3 + 4t^2 - 5t - 2 = 0$...

3t3+4t25t2=03t^3 + 4t^2 - 5t - 2 = 0

Answer

t=1,t=2,t=13t = 1, \quad t = -2, \quad t = -\frac{1}{3}

Explanation

Solution

Given the cubic equation:

3t3+4t25t2=03t^3 + 4t^2 - 5t - 2 = 0
  1. Find a rational root:
    By the Rational Root Theorem, test possible roots ±1, ±2, ±1/3, ±2/3.
    Testing t=1t = 1:

    3(1)3+4(1)25(1)2=3+452=0.3(1)^3 + 4(1)^2 - 5(1) - 2 = 3 + 4 - 5 - 2 = 0.

    Hence, t=1t = 1 is a root.

  2. Factor the polynomial:
    Factor out (t1)(t - 1) from the polynomial. Dividing by t1t - 1 (using synthetic or polynomial division), we get:

    3t3+4t25t2=(t1)(3t2+7t+2).3t^3 + 4t^2 - 5t - 2 = (t-1)(3t^2 + 7t + 2).
  3. Solve the quadratic:
    Factor the quadratic:

    3t2+7t+2=0.3t^2 + 7t + 2 = 0.

    Notice that:

    3t2+6t+t+2=3t(t+2)+1(t+2)=(t+2)(3t+1)=0.3t^2 + 6t + t + 2 = 3t(t+2) + 1(t+2) = (t+2)(3t+1)=0.

    Set each factor to zero:

    t+2=0t=2,t + 2 = 0 \quad \Rightarrow \quad t = -2, 3t+1=0t=13.3t + 1 = 0 \quad \Rightarrow \quad t = -\frac{1}{3}.
  4. Final Answer:
    The solutions are:

    t=1,t=2,t=13.t = 1, \quad t = -2, \quad t = -\frac{1}{3}.

Minimal Explanation:
Find t=1t=1 by testing, factor to get (t1)(3t2+7t+2)=0(t-1)(3t^2+7t+2)=0, then factor the quadratic as (t+2)(3t+1)=0(t+2)(3t+1)=0 to obtain the remaining roots t=2t=-2 and t=13t=-\frac{1}{3}.