平均変化率 = ⊿x/⊿t = x_{2}-x_{1}/t_{2}-t_{1}

平均変化率は，2つの変数の平均を割った値です．
2つの変数の平均が分かれば，それらを割る事によって，平均変化率が求められるのです．
また，分母の変数の単位を限りなく小さくし，分母と分子の平均が分かれば，
これらを割ることによって，微分係数が求められるのです．

微分係数 = dx/dt = t の単位が最小の場合の x の平均値 / t の単位が最小の場合の t の平均値

Mean rate of change = ⊿ x/ ⊿ t = x_{2}-x_{1}/t_{2}-t_{1}

The mean rate of change is the value that fell below the mean of two variables.
A mean rate of change is found by dividing them if it understands the mean of two variables.
Moreover, a differential coefficient is demanded by dividing these
if it lowers the unit of variable of the denominator limitlessly and understand the mean of denominator
and the mean of numerator.

A differential coefficient
= dx/dt
= lim_{t->0} (x-x_{0} / t-t_{0})
= The mean of x when a unit of t is smallest / The mean of t when a unit of t is smallest