x^2 - 7x - 18 = 0?
回答 (11)
2008-01-28 2:42 pm
✔ 最佳答案
(x-9)(x+2)=0x=9,-2
參考: what i got a thumbs down for not showing my work in a simple factorization problem?
i might understand it if you were incapable of simple addition and multiplication... but come on who out there is incapable of seeing that
x^2-7x-18=(x-9)(x+2)
maybe i just assumed most people know how to multiply
most people out there know how to add
and most people know that 0 times anything is 0
you know when i got my degree in mathematics
simplicity and beauty in the answer was far more valued than brute computation...
but hey whatever...
you know if you need to see thirty different steps to understand the solution which can be presented perfectly well in two i can forgive your lack of skill and proudly accept my thumbs down
;)
2008-01-28 2:41 pm
Solve this one by factoring
since the first term is x^2, the expression has the form
(x )(x )
Since the last term is negative, one of the internal operators is positive and the other is negative.
(x + )(x - )
We now need two numbers whose product is 18 and whose difference is 7. 2 and 9 will work
(x + 2)(x - 9) = 0
We now use the zero product property to
x + 2 = 0 or x = -2
x - 9 = 0 or x = 9
since the first term is x^2, the expression has the form
(x )(x )
Since the last term is negative, one of the internal operators is positive and the other is negative.
(x + )(x - )
We now need two numbers whose product is 18 and whose difference is 7. 2 and 9 will work
(x + 2)(x - 9) = 0
We now use the zero product property to
x + 2 = 0 or x = -2
x - 9 = 0 or x = 9
參考: Longtime college math teacher
2015-03-19 7:45 pm
x-7x-18=0
2008-01-28 2:40 pm
(x - 9) (x + 2) = 0
x = 9 or x = -2
x = 9 or x = -2
2008-01-28 2:41 pm
x^2 - 7x - 18 = 0
(x-9)(x+2) = 0
x-9 = 0 or x+2 = 0
x = 9 or x = -2
(x-9)(x+2) = 0
x-9 = 0 or x+2 = 0
x = 9 or x = -2
2015-08-18 6:23 pm
This Site Might Help You.
RE:
x^2 - 7x - 18 = 0?
Solve
RE:
x^2 - 7x - 18 = 0?
Solve
參考: 2 7x 18 0: https://shortly.im/w70pH
2008-01-28 2:51 pm
x^2-7x-12=0
this can be written as:
x^-9x+2x-18=0
x(x-9)+2(x-9)=0
(x+2)(x-9)=0
so
x=9 or x=-2
this can be written as:
x^-9x+2x-18=0
x(x-9)+2(x-9)=0
(x+2)(x-9)=0
so
x=9 or x=-2
2008-01-28 3:30 pm
x^2 - 7x - 18 = 0
(x - 9)(x + 2) = 0
x = 9 or -2
(x - 9)(x + 2) = 0
x = 9 or -2
2008-01-28 2:43 pm
x^2 - 7x - 18= (x-9)(x+2) =0
(x-9)=0 => x= 9
or or
(x+2)=0 => x= -2
(x-9)=0 => x= 9
or or
(x+2)=0 => x= -2
收錄日期: 2021-05-01 22:47:19
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