Find the measure of m arc CD

A. 20
B. 50
C. 60
D. 70

Follow these steps using the algebra tiles to solve the equation −5x + (−2) = −2x + 4. 1. add 5 positive x-tiles to both sides and create zero pairs. 2. add 4 negative unit tiles to both sides and create zero pairs. 3. divide the unit tiles evenly among the x-tiles. x =

How to do this , and can some one explain

Find the roots of the polynomial function f(x) = x^3 + 2x^2 + x