Identify a, b, c: Identify a, b, and c in the quadratic expression 5n2+9n+4. Compare 5n2+9n+4 with ax2+bx+c. a=5b0b1
Find numbers multiply add: Find two numbers that multiply to a∗c (5∗4=20) and add up to b (9).We need to find two numbers that multiply to 20 and add up to 9.After checking possible pairs that multiply to 20 (1 and 20, 2 and 5∗4=200, 5∗4=201 and 5∗4=202), we find that 1 and 20 do not add up to 9, 2 and 5∗4=200 do not add up to 9, but 5∗4=201 and 5∗4=202 do add up to 9.So the two numbers are 5∗4=201 and 5∗4=202.
Rewrite middle term: Rewrite the middle term 9n using the two numbers found in Step 2.5n2+9n+4 can be rewritten as 5n2+4n+5n+4.
Factor by grouping: Factor by grouping.Group the first two terms and the last two terms:(5n2+4n)+(5n+4)Factor out the common factor from each group:n(5n+4)+1(5n+4)
Factor out common binomial: Factor out the common binomial factor.Since both groups contain the factor (5n+4), we can factor it out:(5n+4)(n+1)
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