分析:(1)先化簡,再計(jì)算即可求解;
(2)將除法變?yōu)槌朔,再約分計(jì)算即可;
(3)先算除法,整數(shù)加法;
(4)直接運(yùn)用乘法的分配律計(jì)算;
(5)先算乘法,整數(shù)加法;
(6)(7)(8)按照有理數(shù)混合運(yùn)算的順序,先乘方后乘除最后算加減,有括號的先算括號里面的.
解答:解:(1)12-(-18)+(-7)-15
=12+18-7-15
=30-22
=8;
(2)
-64÷3×=-64×
×
=-12.5;
(3)-63÷7+45÷(-9)
=-9-5
=-14;
(4)
(+-)×(-12)=-
×12-
×12+
×12
=-5-8+9
=-4;
(5)
(-)×(+6)×(-10)×(-)=-3.6+2.5
=-1.1;
(6)8+(-3)
2×(-2)
=8+9×(-2)
=8-18
=-10;
(7)(-5)
3×(-
)+32÷(-2
2)×(-1
)
=(-125)×(-
)+32÷(-4)×(-
)
=75+8×
=75+10
=85;
(8)100+16÷(-2)
4-
-|-100|
=100+16÷16-
-100
=100+1-
-100
=
.
點(diǎn)評:本題考查的是有理數(shù)的運(yùn)算能力.注意:
(1)要正確掌握運(yùn)算順序,在混合運(yùn)算中要特別注意運(yùn)算順序:先三級,后二級,再一級;有括號的先算括號里面的;同級運(yùn)算按從左到右的順序;
(2)去括號法則:--得+,-+得-,++得+,+-得-.