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2007-01-23 01:27:38 · 21 answers · asked by dbanner3 1 in Science & Mathematics ➔ Mathematics
First: factor the equation by finding the greatest common factor > find a common variable and a number divisible with the coefficients > "5x"....
5x(x - 4) = 0
Sec: solve for the x-variables > set both terms to equal "0"....
1. 5x = 0
*Divide both terms by "5"....
5x/5 = 0/5
x = 0
2. x - 4 = 0
*Add "4" to both sides....
x - 4 + 4 = 0 + 4
x = 4
Solution: 0 and 4
2007-01-23 05:10:23 · answer #1 · answered by ♪♥Annie♥♪ 6 · 0⤊ 0⤋
Add 20x to both sides of the equation:
5x^2 - 20x + 20x = 0 +20x
simplify
5x^2 = 20x
Divide by 5
x^2 = 4x
Divide by x (not valid for the case where x might equal 0)
x = 4
Test it:
5*4*4 - 20*4 = 0
80 - 80 = 0
0 = 0
Test the case if x = 0
5*0*0 - 20*0 = 0
0 - 0 = 0
0 = 0
So x = 0 is also valid
2007-01-23 01:54:46 · answer #2 · answered by gamblin man 6 · 0⤊ 0⤋
Factor an 5x out and you will have:
5x ( x - 4 ) = 0
Set each factor equal to 0 and solve:
5x = 0 and x - 4 = 0
x = 0 and x = 4
2007-01-23 01:42:01 · answer #3 · answered by Ray 5 · 1⤊ 0⤋
As you've seen, the roots of this equation are 0 and 4. Factor out 5x to get 5x(x - 4) = 0.
I do have to point out to the others (mostly the first few that gave greivously wrong answers) that if you don't know the material, please don't confuse the asker by giving wrong answers.
This is a second-order polynomial, which means it has two roots. You don't just look at it and assume that 0 is the only root. You need to find the other root.
This kind of hasty solving is exactly what will put you smack dab in the middle of the fast food industry. Have fun with that.
2007-01-23 01:38:47 · answer #4 · answered by Rev Kev 5 · 1⤊ 0⤋
X = 0
2007-01-23 01:30:30 · answer #5 · answered by Anonymous · 0⤊ 5⤋
5x² - 20x = 0
5x(x-4)=0 (take out the 5x)
x= 0 or 4
2007-01-23 01:40:46 · answer #6 · answered by 7 · 1⤊ 0⤋
First things first, divide the whole thing by 5 because this will not change the truth of the equation:
x² - 4x = 0
Now notice that this is divisible by x, so write it as x multiplied by something:
x * (x - 4) = 0
If two things multipied together give you zero, then one or the other of them must itself be zero.
So either x is zero or x - 4 is zero.
If x - 4 is zero, then x is 4.
So x must be 0 or 4.
Read through this and understand it rather than reproducing it in your homework without understanding it.
2007-01-23 01:39:33 · answer #7 · answered by Gnomon 6 · 2⤊ 0⤋
5x(x-4)=0
5x=0 x-4=4
x=0 x=4
2007-01-23 02:09:50 · answer #8 · answered by wendy 2 · 0⤊ 0⤋
you can also factor this into:
x(5x-20)=0
set both terms equal to zero:
x = 0
5x-20 = 0
5x=20
x=4
Solution set is, x = 4, x = 0
2007-01-23 01:32:45 · answer #9 · answered by yhwhlivesinme 2 · 2⤊ 0⤋
factor out x:
x (5x-20) = 0
so one solution is x=0 OR
5x=20 --> x=4
2007-01-23 02:15:18 · answer #10 · answered by sh 1 · 0⤊ 0⤋