Group Terms: Look for common factors in pairs of terms.We will first group the terms into pairs and look for common factors in each pair.Group the terms: (10r3−20r2) and (−r+2).
Factor Common Factor: Factor out the common factor from the first pair of terms.In the first pair 10r3−20r2, the common factor is 10r2.Factor out 10r2: 10r2(r−2).
Factor Binomial: Factor out the common factor from the second pair of terms.In the second pair (−r+2), there is no common factor other than 1. However, we can factor by looking for a term that will help us group the expression into a common binomial factor.We can rewrite −r+2 as −1(r−2) to match the binomial from the first pair.So, −r+2 becomes −1(r−2).
Write Factored Expression: Write the expression with the factored groups.Now we have: 10r2(r−2)−1(r−2).
Factor Common Binomial: Factor out the common binomial factor.We can now factor out the common binomial factor (r−2) from both terms.Factored form: (r−2)(10r2−1).
Recognize Difference of Squares: Recognize that 10r2−1 is a difference of squares.10r2−1 can be factored further since it is a difference of squares: (10r)2−12.Factor the difference of squares: (10r+1)(10r−1).
Write Final Factored Form: Write the final factored form. Combine the factored terms to get the final factored form of the original expression. Final factored form: (r−2)(10r+1)(10r−1).