Probability Density Function problem

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$$ f(x) = \begin{cases} 0 & \text{if $x < 0$} \\ x^2 & \text{if $0 ≤ x < \mu$} \\ α + βx & \text{if $\mu ≤ x ≤ 10$} \\ 0 & \text{if $x ≥ 10$} \end{cases} $$

Considering $\Pr(x < µ) = 1/3$. Questions:

  • Find $\mu$.

  • Find $\alpha$.

  • Find $\beta$.

  • Find the expected value $E(x)$.

I was solving all questions related to probability density functions with not much difficulty, but this one is driving me nuts. What I have done so far:

$$ \int_{0}^{\mu} x^2 \, dx + \int_{\mu}^{10} (\alpha + \beta x) \, dx = 1 $$

which would lead to something like:

$$ (\frac{x^3}{3} \bigg|_{0} ^{\mu}) + (\alpha \cdot x+ \beta \cdot \frac{x^2}{2}\bigg|_{\mu}^{10}) = 1 $$

Anyone know how to proceed?