Let $\lambda \in \mathbb{Z^+}$ be a constant such that the polynomials $f(x,y)=4x^{10+\lambda }+7y^{21+\lambda }-1$ and $g\left(x,y\right)=5x^8+9y^{21}-1$ have common roots that belong to $\mathbb{R}$. Is there a theorem using which the solutions to the polynomial equations can be found?
I have tried using the gcd of the polynomials via wolfram, the answer was 1. That doesn't make sense because some of the next questions I have take that there are common roots as granted... I have tried using Groebner bases but failed, and U also tried converting the system to a linear one and thus using matrices. That was a desperate try and doesn't make sense to me, but still did it.