A math puzzle

[Alidar Jarok]

Others have explained it, but if you write out the squares for (3 - 4) and (5 - 4) it becomes obvious:

(3 - 4)^2 becomes (3 - 4) (3 - 4)

So it would be:
(3 - 4) (3 - 4) = (5 - 4) (5 - 4)
There's no way for that to turn into
3 - 4 = 5 - 4

 

[M'Sharak]

...

Totally off-topic, but I just have to ask: what kind of spider is the one in your avatar, Asbo Zaprudder? It's pretty!

A jumping spider - family Salticidae - although I'm not sure which one of the approx 5000 species.

I think it's this kind, especially if the ID which goes with the source image is anything to go by.

 

[Asbo Zaprudder]

These puzzles usually boil down to division by zero or multiplication by zero in one of the steps. I hadn't seen this variant before.

ETA: Thanks, M'Sharak.

 

[rhubarbodendron]

me neither. A very nice variation of the old math trick

I had suspected it to be a Salticidae - the eye position is typical. In my country we only have very small black and white striped ones (Salticus scenicus) and even tinier brown ones with 4 dots (Sitticus pubescens). Both species have black eyes with blue reflections. The green reflection in your avatar-spider's eyes is quite attractive

 

[JarodRussell]

3-4 is not equal to 5-4, and one can also completly above any line before that.