According to the Rational Root Theorem, for a polynomial equation , the possible rational roots are of the form , where is a factor of the constant term and is a factor of the leading coefficient .
For the equation , the leading coefficient is 10 and the constant term is -10.
Factors of -10 are ±1, ±2, ±5, ±10.
Factors of 10 are ±1, ±2, ±5, ±10.
So the possible rational roots are ±1/1, ±1/2, ±1/5, ±1/10, ±2/1, ±2/2 (which simplifies to ±1), ±2/5, ±2/10 (which simplifies to ±1/5), ±5/1, ±5/2, ±5/5 (which simplifies to ±1), ±5/10 (which simplifies to ±1/2), ±10/1, ±10/2 (which simplifies to ±5), ±10/5 (which simplifies to ±2), ±10/10 (which simplifies to ±1).
Now we test these possible roots one by one.
Testing :
Substitute into the equation: .
Testing :
Substitute into the equation: