Identify a, b, c: Identify a, b, and c in the quadratic expression 2n2+11n+9. Compare 2n2+11n+9 with ax2+bx+c. a=2b0b1
Find numbers multiply and add: Find two numbers that multiply to a∗c (2∗9=18) and add up to b (11).We need to find two numbers that multiply to 18 and add up to 11.After checking possible pairs that multiply to 18 (1 and 18, 2 and 2∗9=180, 2∗9=181 and 2∗9=182), we find that 2 and 2∗9=180 are the numbers we are looking for because 2∗9=185.
Rewrite middle term: Rewrite the middle term 11n using the two numbers found in Step 2.We can express 11n as the sum of 2n and 9n.2n2+11n+9 becomes 2n2+2n+9n+9.
Factor by grouping: Factor by grouping.First, group the terms: 2n2+2n + 9n+9.Now, factor out the common factors from each group.From the first group, we can factor out 2n: 2n(n+1).From the second group, we can factor out 9: 9(n+1).
Write factored form: Write the factored form of the expression.Since both groups contain the common factor (n+1), we can factor this out.The factored form is (2n+9)(n+1).
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