From.1's Maths

1)
Let x be the required number.
20-2x=4^2
20-2x=16
2x=4
x=2
Hence, the required number is 2.

2)
Let x-2,x,x+2 be the three consecutive even numbers.
(x-2)+x+(x+2)=42
3x=42
x=14
Hence, the three required consecutive even numbers are 12, 14 and 16.

1. 20 - 2a = 4^2
20 - 2a = 16
2a = 4
a = 2

2. let x be the first consecutive even nunber, (x + 2) be the second consecutive even nunber, (x + 4) be the third consecutive even nunber

x + (x + 2) + (x + 4) = 42
3x + 6 = 42
3x = 36
x = 12

Therefore, three consecutive even nunbers are 12, 14 and 16.

第2條:
let x be a small no,
x+x+2+x+4=42
3x+6=42
x=12

所以the three consecutive even numbers are 12,14,16.

唔知對唔對!!!!!

1]]Let X be the number.
2
20-2X=4
20-2X=16
20-16=2X
4=2X
4/2=X
X=2
So the number is 2.

2]]Let X be the number.
X+(X+1)+(X+2)=42
3X+3=42
3X=42-3
3X=39
X=39/3
X=13
So the number is 13.

1. let x be the number
20-2x=4^2
20-16= 2x
4=2x
x=2

2. let x be first no. , (x+2) be second no. and (x+4)be third no.
x+(x+2)+(x+4)=42
x+x+2+x+4=42
3x=42-4-2
3x=36
x=12
so the first no.x=12,second no.=x+2= 14 and the third no. x+4 =16

let n be the number

.................2
1.20-n+2=4

2.n+1+n+2+n+3=42

1) 20-2a=4×4
20-2a=16
a=2



2) y+(y+2)+(y+4)=42
3y+6=42
3y=36
y=12

第2條"
let x be the smallest number
x+x+1+x+2=42
3x+3 =42
3x=42-3
3x =39
x=13

∴the numbers are 13,14,15.


第1條(唔知岩唔岩)
let the number be x

20-x-2=4square
20-x-2=4×4
18-x =16
-x =-2
x=2

∴the number is 2