How to find inverse of summation for inverse transform sampling?

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How can I find the inverse of summation for this

$u=\sum_{h=1}^{n-j} {n-j \choose h}(-1)^h \; \frac{1}{j+h} > (1-e^{-\lambda_1X})^{\alpha \alpha_1(j+h)}$

where $x>0 , \alpha, \alpha_1 >0$

I want to find X alone in left hand side like this

$U=F(x)$ and I want to get X equals the inverse function of U,$\;\;$ $X=F^{-1}(U)$ , see the following example

$U=(1-e^{-\lambda_1X})^{\alpha \alpha_1}$

$U^{\frac{1}{\alpha \alpha_1}}=1-e^{-\lambda_1X}$

$1-U^{\frac{1}{\alpha \alpha_1}}=e^{-\lambda_1X}$

$ln(1-U^{\frac{1}{\alpha \alpha_1}})=-\lambda_1X$

$X=\frac{ln(1-U^{\frac{1}{\alpha \alpha_1}})}{-\lambda_1}$

How can I do that in my expression?

Thanks in advance