第2页

信息发布者:
解:
$\begin{aligned}(2025-\pi)^0-(\frac{1}{3})^{-2}+(-1)^{2025}&=1 - 9 + (-1)\\&=1 - 9 - 1\\&=-9\end{aligned}$
解:
$\begin{aligned}(y-x)^2·(x-y)^3·(y-x)^4&=-(x-y)^2·(x-y)^3·(x-y)^4\\&=-(x-y)^{2+3+4}\\&=-(x-y)^9\end{aligned}$
解:
$\begin{aligned}5x^4·(-x)^2-(2x^2)^3&=5x^4·x^2 - 8x^6\\&=5x^6 - 8x^6\\&=-3x^6\end{aligned}$
解:
$\begin{aligned}(-2x)^5-(-x)^3·(-x)^2&=-32x^5 - (-x^3)·x^2\\&=-32x^5 + x^5\\&=-31x^5\end{aligned}$
解:原式​$=a^{2+4}-(-8a^{2×3})+a^{8-2}$​
​$=a^6+8a^6+a^6$​
​$=10a^6$​
解:原式​$=9a^6\ \mathrm {·} a^3-125a^9+a^{-2+11}$​
​$=9a^9-125a^9+a^9$​
​$=-115a^9$​
解:因为​$a + 4 = -3b,$​
所以​$a + 3b = -4,$​
​$ \begin {aligned}3^a×27^b&=3^a×3^{3b}\\&=3^{a+3b}\\&=3^{-4}\\&=\frac {1}{81}\end {aligned}$​