can anybody solve this, i don't really know if its reverse factoring or what but any help would be greatly appreciated, thanks
2007-03-08 12:45:02 · 10 answers · asked by dale 1 in Science & Mathematics ➔ Mathematics
(3x)(x - 4)(x + 7) = 0
The product of 3 numbers is zero. So al least one number must be equal to zero.
To solve this, one must set each expression in the brackets to zero and solve for x, nothing more.
Put 3x = 0
x = 0/3 = 0
Put x - 4 = 0
x = 0 + 4 = 4
Put x + 7 = 0
x = 0 - 7 = -7
The three possible values of x are 0, 4 and -7. Substituting any of these values in the equation will satisfy this equation.
2007-03-08 13:05:15 · answer #1 · answered by Akilesh - Internet Undertaker 7 · 0⤊ 0⤋
When you have ONLY products like this case you solve each product, since when at least one is zero, the equation is solved:
3x(x-4)(x+7)=0
if 3x=0, that's when x=0
if x-4=0, that's when x=4
if x+7=0, that's when x=-7.
Those are the 3 solutions.
Now, if you had: 3x(x-4)(x+7) +1 =0 , this can't be applied, because you don't have only products, but also an addition (+1). In this case you must expand and try to find the factors of the product.
2007-03-08 12:51:35 · answer #2 · answered by Anonymous · 0⤊ 0⤋
this is zero when any of the factors is zero
so x = 0 x-4 = 0 or x+7 = 0
which means x=0, 4, -7
2007-03-08 12:53:11 · answer #3 · answered by Anonymous · 0⤊ 0⤋
x= 0, 4, -7
2007-03-08 12:55:53 · answer #4 · answered by scootergarrett 2 · 0⤊ 0⤋
hmm... what is needed to solve here? is it the roots?
if its the roots, first equate all the factors to 0.
3x = 0 x-4 = 0 x+7 = 0
then solve for x..
x = 0 x = 4 x = -7
but if you want to expand it.... then, use the foil method to mulitply x-4 and x+7...
3x [ x^2 -4x + 7x - 28] = 0
3x [ x^2 + 3x - 28] = 0
then distribute 3x...
3x^3 + 9x^2 - 84 = 0
2007-03-08 13:01:10 · answer #5 · answered by Anonymous · 0⤊ 0⤋
x=0
x=4
x=-7
If x=0, then the 3x term =0 so when multiplying out, everything becomes 0
If x=4, the x-4 term becomes 0, same result.
if x=-7, the x+7 term will be zero
that's all you got to do
2007-03-08 12:51:04 · answer #6 · answered by Chris R 1 · 0⤊ 0⤋
3x(x-4)(x+7) = 0
3x =0 so x=0
x-4 =0 so x=4
x+7 =0 so x= -7
2007-03-08 12:50:18 · answer #7 · answered by jaybee 4 · 0⤊ 0⤋
Yea, what they said. 0 or 4 or -7, relating to the zero principle.
2007-03-08 12:51:54 · answer #8 · answered by Mike L 2 · 0⤊ 0⤋
it's just multi-step multiplying
3x(x-4)(x+7) = 0
3x(x^2+3x -28) = 0
3x^3+9x^2-84x = 0
x = 0, 4, -7
2007-03-08 12:50:29 · answer #9 · answered by Brian F 4 · 0⤊ 0⤋
3x^3 + 6x^2 - 84x = 0
fyi: ^2 means squared
2007-03-08 12:57:14 · answer #10 · answered by cat_eyes<\>.</> 1 · 0⤊ 0⤋