Can you find the error out in this funny mathematical exercise?

Question

16 - 36=25 - 45
16-36+81/4 = 25 - 45 + 81/4
(4-9/2)*(4-9/2)=(5-9/2)*(5-9/2)

wow! every thing is nice but this gives us 4=5
great! can u point out the error.

Answer 1

He He :)

Had me thinking for sometime!

But the answer is darnedly simple:

9/2 = 4.5

So, 4 - 9/2 = 4 - 4.5 = -0.5
And, 5 - 9/2 = 5 - 4.5 = 0.5

And (-0.5)^2 = (0.5)^2. But this does not mean: -0.5 = 0.5

You cannot equate squares directly like that. Whenever u equate two squares, always a "plus or minus" comes into the picture!

i.e., if a^2 = b^2, then it DOES NOT mean a = b.
It means: a = plus or minus b. (a = b OR a = -b)

Answer 2

There is no error: the two expressions are actually equal.

4 - 9/2 = -1/2

5 - 9/2 = 1/2

Squaring both of these gives the same result.

Answer 3

There is no error because

(4-9/2)*(4-9/2)=1/4

and

(5-9/2)*(5-9/2)=1/4

both r equal

Answer 4

The error is that you can't take 5and subtract9 and you can't take16 and- 36 25-45is imposslible.5-9/20is nothing because it is 5-18.
There is a lot of errors in this too much too point out .

Answer 5

when you take square root therecan be two values +/-
only one of the values may satisfy the equation
also (a-b)^2=(b-a)^2
like in this case
rt of(4-9/2)^2=>rt of(9/2-4)^2=1/2
rt of (5-9/2)^2=1/2
so 9/2-4=5-9/2
which is correct

Answer 6

16-36=25-45
16-36+81/4=25-45+81/4
(1-9/2)*(4-9/2)=(1-9/2)*(5-9/2)

Answer 7

very simple.. see the folloing

4 - 9/2 = -0.5

5 - 9/2 = 0.5

and this is resulting is diffence of 1

Answer 8

i have lost i could not find error.

there is n error

i) -20 = -20 (is true)

ii) -20+81/4 = -20+81/4
=> (-80+81)/4 = (-80+81)/4
=> -1/4 = -1/4 (is true )

iii) (4-4.5) * (4-4.5) = (5-4.5) * (5-4.5)
=> -0.5 x -0.5 = 0.5 x 0.5
implies 0.25 = 0.25 again its true

.where did u get 4=5 dear please tell me i wanna know

Answer 9

16=20 u fool.

Answer 10

square of (-a) is a^2
square of (+a) is also a^2
whether we can say (-a) equals to (+a)
If it is true, the following example will clear ur doubt
Suppose you have given Rs.'a' to me as a loan
For repayment, you only have to give me Rs. 'a'