7X-2X-1/2點計?要步驟

7x-2x-1/2
=5x-0.5
x=0.5/5
x=0.1


唔係ga,你要先將個中括號變成小括號先,再將8乘個個小括號再-8,俾左個步驟你睇,咁樣你會明d
8[5(2+2)]-8
=8[5(4)]-8
=8(20)-8
=160-8
=152

1. 7X-2X-1/2
=5X-0.5

2 7X-2X-1/2
E題答案系21,求X
7X-2X-1/2=21
5X-0.5=21
5X=21.5
X=4.3

3. 8[5(2+2)]-8
=8[5(4)]-8
=8(20)-8
=160-8
=152

4 8[5(2+2)]-8甘既題目8系咪乘所有中括號里面既野?(包括小括號?)
甘既題目8(前者8)係在拆除小括號後再乘入去的
*先乘除後加減

如果x係代數，
7X-2X-1/2
=5X-1/2
如果X係解乘，
7x-2x-0.5
=7x1 <-2x-0.5會負負得正>
=7

8[5(2+2)]-8
=8(20)-8
=160-8
=152

2007-11-06 18:49:37 補充：
7X-2X-1/2 E題答案系21,求X 呢條問題係咪未問完??

7x-2x-1/2
=4x-1/2
8[5(2+2)]-8
=8[10+10]-8
=8*20-8
=160-8
=152

2007-11-07 19:50:47 補充：
括號的计算是由小到大的计算的.....例如:a[b(c d)]=a[bc bd]=abc abd =======

7X-2X-1/2
=5X-0.5

8[5(2+2)]-8
=8[5(4)]-8
=8(20)-8
=160-8
=152
(8唔系要乘所有中括號里面既野。要先解決小括號,再解決較大的括號)

7X-2X-1/2
=5X-0.5

8[5(2+2)]-8
=8(10+10)-8
=80+80-8
=160-8
=152