How do i identify a rational number? what does a rational number look like?

The factorization of 8x3 -125 is (2x-5)(jx2 +kx+25)

What is the next step in the given proof? choose the most logical approach. a. statement: m 1 + m 2 + 2(m 3) = 180° reason: angle addition b. statement: m 1 + m 3 = m 2 + m 3 reason: transitive property of equality c. statement: m 1 = m 2 reason: subtraction property of equality d. statement: m 1 + m 2 = m 2 + m 3 reason: substitution property of equality e. statement: 2(m 1) = m 2 + m 3 reason: substitution property of equality

How many and of which kind of roots does the equation f(x)=2x^4−9x^3+17x^2−16x+6 have?