The second round has x * x = x 2 branches.
The third round has x 2 * x = x 3 branches.
By analogy, the nth theory (n is a positive integer) has x branches.
Or:
The first time is 1, the second time is 2, and the third time is 4.
That is, geometric progression sum with a 1= 1 and the common ratio of 2.
1*( 1-2^n)/( 1-2)=2^n- 1
Extended data:
The establishment of a quadratic equation with one variable must meet three conditions at the same time:
(1) is the whole equation, that is, both sides of the equal sign are algebraic expressions, if there is a denominator in the equation; And the unknown is on the denominator, then this equation is a fractional equation, not a quadratic equation. If there is a root sign in the equation and the unknown is within the root sign, then the equation is not a quadratic equation (it is an irrational number equation).
(2) contains only one unknown number;
③ The maximum number of unknowns is 2.
Baidu Encyclopedia-One-variable Quadratic Equation