展开 n^2-((n(n+1))/2)+n

解答

展开

n^{2} - (\frac{n ( n + 1 )}{2}) + n

n^{2} - \frac{n ^{2}}{2} - \frac{n}{2} + n

求解步骤

n^{2} - (\frac{n ( n + 1 )}{2}) + n

去除括号:

(a) = a

= n^{2} - \frac{n ( n + 1 )}{2} + n

乘开

n (n + 1) : n^{2} + n

= n^{2} - \frac{n ^{2} + n}{2} + n

使用分式法则:

\frac{a \pm b}{c} = \frac{a}{c} \pm \frac{b}{c}

\frac{n ^{2} + n}{2} = - (\frac{n ^{2}}{2}) - (\frac{n}{2})

= n^{2} - (\frac{n ^{2}}{2}) - (\frac{n}{2}) + n

去除括号:

(a) = a

= n^{2} - \frac{n ^{2}}{2} - \frac{n}{2} + n

e x p an d (x + x^{2}) x ln (x) - x

e x p an d T (- 2 (1, 0, 0) + 3 (0, 1, 0) + 1 (0, 0, 1))

e x p an d i^{3}

so l v e f or f, f = δ (x - 2) e^{2 x}

e x p an d (3 x^{2} - 5 x) e^{2}