2x2-13x-7=0 It is a quadratic equation and the directions say to factor it! I am taking an online class and my teacher is off today so i cannot call her. Please no cracks on doing my own homework.
2007-01-02 05:07:28 · 3 answers · asked by Brad 1 in Science & Mathematics ➔ Mathematics
2x^2-13x-7=0 I forgot to add the exponenet mark!
2007-01-02 05:08:48 · update #1
2x² - 13x - 7 = 0
Since the last number is negative, you know that you'll need one root to be positive and one to be negative.
Also, since the number in the middle (-13) is almost the product of the other two (2 x -7 = -14), it makes sense to try to arrange the factors so that the 2 multiplies by a -7 when you FOIL:
(2x + 1)(x - 7) = 0
x = -1/2 or x = 7
(Yes, I missed the - sign on the 1/2 originally. I fixed it.)
2007-01-02 06:13:21 · answer #1 · answered by Jim Burnell 6 · 0⤊ 1⤋
factor you want facor you get
try the divisors of 7 as solution ( x= 1 x = 7 )
for 7 we get
2*49 -13*7 - 7 = 0
98 - 91 - 7 = 0 ? yes.
so 7 is a solution and thus is (x-7) a factor of (2x2-13x-7)
the other try x = 1 is not.
factorising ( by looking )
(x-7)(2x + a ) = 2x2-13x-7 ,
write out and solve the a
2007-01-02 14:14:30 · answer #2 · answered by gjmb1960 7 · 0⤊ 2⤋
2x^2 - 13x - 7 = 0
(2x + 1) * (x - 7) = 0, check this by multiplying it out for yourself.
Therefore 2x + 1 = 0, or x - 7 = 0.
Simplifying, x = -1/2 or x = 7
(shame, Jim Burnell got one sign wrong)
2007-01-02 17:11:43 · answer #3 · answered by bh8153 7 · 0⤊ 0⤋