I really need help with this one.
2007-07-04 10:49:20 · 4 answers · asked by casey c 1 in Science & Mathematics ➔ Mathematics
12y^2 - 13y - 72
This polynomial doesn't factor.. which means it is prime.
If you multiply 12y^2 by -72 you get -864y^2
In order for this polynomial to factor you must divide the middle term (-13x) into two terms that have a product of -864y^2. There are no two terms that have a product of 864y^2 that also have a sum of -13y.
2007-07-04 11:01:10 · answer #1 · answered by suesysgoddess 6 · 1⤊ 0⤋
The discriminant is
d = 13^2 + 4*12*72
= 169 + 3456
= 3625
As this is not a perfect square, the factors cannot be found by inspection.
Solve the equation 12y*2 -13y - 72 = 0 using the quadratic formula:
y = ( 13 +/- sqrt(3625) ) / 24
y = ( 13 +/- 5sqrt(145) ) / 24
The factors of the LHS are therefore:
12( y - [13 - 5sqrt(145)] / 24 )( y - [13 + 5sqrt(145)] / 24 ).
2007-07-04 18:16:53 · answer #2 · answered by Anonymous · 0⤊ 0⤋
That one's prime. You would need factors of 12*72 = 864 that differ by 13. Closest you can get is 24*36, which differ by 12.
2007-07-04 17:58:00 · answer #3 · answered by Philo 7 · 1⤊ 0⤋
You're stuck with the quadratic formula for this one.
a = 12, b = -13, and c = -72
good luck!
2007-07-04 17:59:59 · answer #4 · answered by birdwoman1 4 · 0⤊ 0⤋