Identify Common Factors: Look for common factors in the first two terms and the last two terms separately.For the first two terms, 20z3 and 10z2, the common factor is 10z2.For the last two terms, 18z and 9, the common factor is 9.
Factor Out Common Factors: Factor out the common factors from the first two terms and the last two terms.Factor out 10z2 from 20z3+10z2 to get 10z2(2z+1).Factor out 9 from 18z+9 to get 9(2z+1).
Write New Expression: Write down the new expression using the factored terms.The new expression is 10z2(2z+1)+9(2z+1).
Factor Out Binomial Factor: Factor out the common binomial factor (2z+1) from the two terms.The factored form is (2z+1)(10z2+9).