flee0308 wrote: No, no, thats not the point. This is not to show a=b. The point is to find the mistake in the equaion, and this is it.
Boredness wrote:I found this on the net...
Given: a = b
a^2 = ab
a^2 - b^2 = ab - b^2
(a+b) (a-b) = b(a-b)
(a+b) = b
(a+a) = a
2a = a
2 = 1
WTF?
If you look at step 3, you would know that both sides of the equation is divided by (a-b). That cannot be done, as a=b, which means (a-b)=(a-a)=0. Division by Zero is not allowed in any case. Thus, the equation should be continued like this:
Given: a = b
a^2 = ab
a^2 - b^2 = ab - b^2
(a+b) (a-b) = b(a-b)
(a+b)(a-a)=b(a-a)
(a+b)*0=b*0
0=0
guyz92: There is NO such thing as "crossing out" in maths. "crossing out" is a just a more convenient mean of division. Further more, there is no Law of Indices about crossing out. Oh and there is a shorter step of solving the equation if it was a proving sum.
Proof that a=b from a^2=ab.
a^2=ab
Dividing both sides by a, a=b
(a+b)(a-b)=b(a-b)
(a+b)=[b(a-b)]÷(a-b)
Therefore it became (a+b)=b.
If above still dun understand, Sub (a-b) as big U.
(a+b)(U)=b(U)
(a+b)=[b(U)]÷(U)
(a+b)=b
flee0308 wrote: No, no, thats not the point. This is not to show a=b. The point is to find the mistake in the equaion, and this is it.
Boredness wrote:I found this on the net...
Given: a = b
a^2 = ab
a^2 - b^2 = ab - b^2
(a+b) (a-b) = b(a-b)
(a+b) = b
(a+a) = a
2a = a
2 = 1
WTF?
If you look at step 3, you would know that both sides of the equation is divided by (a-b). That cannot be done, as a=b, which means (a-b)=(a-a)=0. Division by Zero is not allowed in any case. Thus, the equation should be continued like this:
Given: a = b
a^2 = ab
a^2 - b^2 = ab - b^2
(a+b) (a-b) = b(a-b)
(a+b)(a-a)=b(a-a)
(a+b)*0=b*0
0=0
guyz92: There is NO such thing as "crossing out" in maths. "crossing out" is a just a more convenient mean of division. Further more, there is no Law of Indices about crossing out. Oh and there is a shorter step of solving the equation if it was a proving sum.
Proof that a=b from a^2=ab.
a^2=ab
Dividing both sides by a, a=b
(a+b)(a-b)=b(a-b)
(a+b)=[b(a-b)]÷(a-b)
Therefore it became (a+b)=b.
If above still dun understand, Sub (a-b) as big U.
(a+b)(U)=b(U)
(a+b)=[b(U)]÷(U)
(a+b)=b
PS this is not indices, it is sec 2 math.
This is not indices. This is not sec 2 math. This is the very basic rule of division. You cannot divide by zero. Nor can you times 0 first, then divide by 0. 0/0 is neither 0, nor 1. It is undefined (or error2, if you use a calculator)
(a-b)=0, and you cant divide by 0.
Last edited by flee0308 on Thu Dec 10, 2009 10:43 am, edited 1 time in total.
No, no, thats not the point. This is not to show a=b. The point is to find the mistake in the equaion, and this is it.
Boredness wrote:I found this on the net...
My Brain Brust into Flames. Anyways you learn this crap in Singapore. In Malaysia Every Education Kinda Slow but less pressure 
Malaysia Education in Math sucks I'm 12 And Nothing much to learn 
=="