SOLUTION: hi :) how do i solve.. 1. 2n^2+5n-42 2. 5x^2+35x+30 If you could help i would really appreciate it and thanks 4 your help! :)

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: hi :) how do i solve.. 1. 2n^2+5n-42 2. 5x^2+35x+30 If you could help i would really appreciate it and thanks 4 your help! :)       Log On


   

Question 417682: hi :)
how do i solve..
1. 2n^2+5n-42
2. 5x^2+35x+30
If you could help i would really appreciate it and thanks 4 your help! :)


Found 2 solutions by sudhanshu_kmr, dnanos:
Answer by sudhanshu_kmr(1152) About Me  (Show Source):
You can put this solution on YOUR website!
1. 2n^2+5n-42
= 2n^2+12n - 7n -42
= 2n(n+6) -7(n+6)
= (2n-7) (n+6)



2. 5x^2+35x+30
= 5x^2+30x+ 5x+30
= 5x(x+6) + 5(x+6)
= (5x+5)(x+6)

Answer by dnanos(83) About Me  (Show Source):
You can put this solution on YOUR website!
2n%5E2%2B5n-42%29
We multiply -42%2A2=84
We try to find two numbers having sum 5 and product 84,that is
select from the factors of -84
-1*84
-2*42
-3*28
-4*21
-6*14
-7*12 etc.
Since -7+12=5 we stop here this search of number pairs and we have
2n%5E2%2B%28-7%2B12%29n-42%29=
2n%5E2-7n%2B12n-42=
n%282n-7%29%2B6%282n-7%29=
%282n-7%29%28n%2B6%29
For the other expression
5x%5E2%2B35x%2B30=
5%28x%5E2%2B7x%2B6%29
1*6
2*3
3*2
etc.... stop... we found 1%2A6=6 and 1%2B6=7
going back to the expression we obtain:
5%28x%5E2%2B%281%2B6%29x%2B6%29=
5%28x%5E2%2Bx%2B6x%2B6%29=
5%28x%28x%2B1%29%2B6%28x%2B1%29%29=
5%28x%2B1%29%28x%2B6%29