<    1      2    >

---

Tautology

A calculation is a tautology. In mathematics, this means that at the left and right of the equal sign (=) the same is stated.

 

---

Example 1

Some simple calculations show

2 + 3 = 5     or     6 = 2 × 3     or     

If left and right are not identical you have made a mistake. That is it.

 

---

Example 2

You can solve the equation

x² = 2^x

as for x = 2 it gives

2² = 2²     ⇒     4 = 4

and that is correct. You can easily see that. But there are more solutions. By trial and error you can find them.

 

---

Example 3

Substituting the definitions of the sine and the cosine in Euler's formula gives

 

---

العربية   Deutsch   Español   Français   Nederlands   中文   Русский