Identify trinomial: Identify the trinomial to be factored, which is 5x2+18x+9.
Find two numbers: Look for two numbers that multiply to give the product of the coefficient of x2 term (5) and the constant term (9), which is 5×9=45, and add up to the coefficient of the x term (18).
Determine numbers: Find the two numbers that meet the criteria from Step 2. The numbers 15 and 3 multiply to give 45 and add up to 18.
Rewrite middle term: Rewrite the middle term 18x using the two numbers found in Step 3 as the sum of two terms: 15x and 3x. The trinomial becomes 5x2+15x+3x+9.
Factor by grouping: Factor by grouping. Group the first two terms and the last two terms: (5x2+15x)+(3x+9).
Factor out common factor: Factor out the greatest common factor from each group. From the first group, factor out 5x, and from the second group, factor out 3: 5x(x+3)+3(x+3).
Final factorization: Since both groups contain the common factor (x+3), factor it out: (x+3)(5x+3).