4x^2-16x=0?

4x^2-16x=0 Factor out a 4x

4x(x-4)=0 Set both 4x and x-4 equal to 0

4x=0 x-4=0 Solve for x

x=0 x=4

2006-10-30 16:12:18 · answer #1 · answered by futureastronaut1 3 · 0⤊ 0⤋

This kind of question should take less than 30 seconds to give an answer. After I finished the test I'd be sure to check my answers, since I'd surely have a few minutes of extra time.

First of all, it should be easy to see that if x=0, then the equation is true. Since that's true, then you can get rid of one of the x's.

Then you have x=0 and 4x^2/x - 16x/x = 0/x.
Is it easy to see that it's 4x - 16 = 0?

Add 16 to both sides, 4x - 16 + 16 = 0 + 16.
4x = 16
4x/4 = 16/4
x = 4

Thus I see x = 0 and x = 4 as the two solutions.

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So now I finished the test, but I have a few minutes before it's over. I'll check my answers...

plugging in x = 0: 4 * 0^2 = 0; 16 * 0 = 0; ok, this answer is correct.

plugging in x = 4: 4 * 4 ^2 = 4 * 16; 16 * 4 = the same, so I just eyeball to check if there are any other possibilities. Hopefully I remember that if there's a ^2 then there are 2 solutions or less, so I'm finished. Otherwise, I just think about -4 and if it would be a solution. Since it's not, I'll just move on to check the other questions. Good job!

2006-10-31 03:17:59 · answer #2 · answered by Tom A 3 · 0⤊ 0⤋

Separate out 4x from the equation

4x (x-4) = 0

after factorising

4X = 0
thus, x = 0

and also,
(x - 4)=0
x = 4 (after taking 4 to the other side... the sign changes)

the final answer to this is x = 0 or 4.

2006-10-30 16:19:29 · answer #3 · answered by Sindhoor 2 · 0⤊ 0⤋

Take a 4x out so you get 4x(x-4) = 0.

Your answer is that X = 0, 4.

Since anything multpilied by 0 = 0
4*0 = 0 so 0(0-4)=4
and 4-4=0 so 4*4(0) = 0

2006-10-30 16:15:16 · answer #4 · answered by Roman Soldier 5 · 0⤊ 0⤋

firstly,4x^2-16x=4x(x-4)=0 so either 4x=0 or x-4=0 therefore
the answer is x=0 or x=4

2006-10-30 17:59:31 · answer #5 · answered by peterwan1982 2 · 0⤊ 0⤋

4x^2-16x=0

divide both sides of the eq by 4
x^2 - 4x = 0
x(x-4) = 0

equate both terms to 0

x=0
x-4 = 0

so x = 0 and 4

2006-10-30 20:22:38 · answer #6 · answered by lazareh 2 · 0⤊ 0⤋

4x^2-16x=0
4(x^2-4X)=0
4X(X-4)=0

4X=0 & (X-4)=0

4X=0 then X=0
X-4=0 then X=4

So x has two value X=0 , X=4

2006-10-30 16:27:36 · answer #7 · answered by safrodin 3 · 0⤊ 0⤋

4x^2-16x=0
4x(x-4)=0
x=4
or
x=0

2006-10-30 16:45:28 · answer #8 · answered by yupchagee 7 · 0⤊ 0⤋

4x^2 - 16x = 0
x (4x - 16) = 0

x1 = 0
4x = 16
x2 = 4

2006-10-30 16:25:04 · answer #9 · answered by Dr. J. 6 · 0⤊ 0⤋

x=0
x= 4

2006-10-30 16:48:38 · answer #10 · answered by Mr. X 3 · 0⤊ 0⤋

12 answers