我有些 F.1 maths 唔識做,幫下我呢?

-3{-2-5[+2+(-5)]}+4
=-3[-7(2-5)]+4 <---呢度錯左,應該先乘除後加減
=-3(-7*-3)+4
=-3*21+4
=-63+4
=-59

corrected ans:

=-3[-2-5(-3)]+4
=-3[-2-(-15)]+4
=-3[13]+4
=-35


-2[3(2m-3)+2]=m+1
-2(6m-11m-m=1+2 <--- 呢度錯左
6m-m=3+11
6m/6=14/5
m=2.8

corrected ans:

-2[6m-9+2]=m+1
-2[6m-7]=m+1
-12m+14=m+1
13m=13
m=1


2n+1/6-3n-2/2=7/3
2n+1-3n-2*3=14 <--呢度有問題, 3n都要乘3架
2n-3n-6=14-1
-n=13-6
n=-7

corrected ans:

(2n+1)-(3n-2)*3=14
2n+1-(9n-6)=14
2n+1-9n+6=14
-7n+7=14
-7n=7
n=-1

The sum of 4 consecutive even numbers is 108. What are the four numbers ?

let y be the smallest number
then the four numbers are y,y+2,y+4,y+6
sum of the numbers is 108

y+(y+2)+(y+4)+(y+6)=108
4y+12=108
4y=96
y=24

the four numbers are 24,26,28,30

Let x be the smallest number amoung the 3 consecutive number,

x + (x+2) + (x+4) + (x+6) = 108
4x + 12 = 108
4x = 96
x = 24

Therefore the four number to be 24 26 28 30

Back Check: 24 + 26 + 28 + 30 = 108