Question

Dengan caraaanya ya .

Answer 1

1)
x/4 + y/3 = 1 ---> kalikan 12 --> 3x + 4y = 12 ...(1)
x/3 + y/2 = 1 ---> kalikan 6  --> 2x + 3y = 6 ......(2)
.
3x + 4y = 12  
2x + 3y = 6
.......................(-)
x + y = 6

2) 
1/3 x + 2/5 y = 4/15 --> kali 15 ---> 5x + 6y = 4
3/4 x - 1/2 y = 2  ---> kali 4  --> 3x - 2y = 8
.
5x + 6y = 4 ..kali 1
3x - 2y = 8... kali 3
.
5x +6y = 4
9x - 6y = 24
jumlahkan
14x = 28 -->x = 2
3x - 2y = 8 --> 3(2) - 2y = 8 --> -2y = 8-6 = 2
y = -1
(x,y) = (2, -1)

3. misal x+1 = a  dan y-2 = b
(x+1)/2 - (y-2)/3 = 3....kalikan 6--> 3(x+1)- 2(y-2) = 18
(x+1)/3 +(y-2)/5 = 2...kalikan 15 -> 5(x+1)+3(y-2) = 30
.
3(x+1)- 2(y-2) = 18 -->
3x + 3 - 2y + 4 = 18
3x - 2y + 7 = 18
3x - 2y = 18-7
3x - 2y = 11
.
5(x+1)+ 3(y-2) = 30 --> 5x + 5 + 3y - 6 = 30
5x + 3y - 1 = 30
5x + 3y = 31
.
3x - 2y = 11 ...kali 3 
5x + 3y = 31..kali 2
.
9x - 6y = 33
10x +6y = 62
........(+)
19x = 95 -->x = 5
3x - 2y = 11--> 3(5) - 2y = 11
-2y = 11- 15 = - 4
y = 2

x - y = 5 - 2 = 3

4)
misl a = 1/x, b= 1/y
5/x + 6/y = 3 --> 5a + 6b = 3
3/x + 5/y = 6 --> 3a +  5b = 6
.
5a + 6b = 3 .....kali 5
3a + 5b = 6 .....kali 6
.
25a + 30b = 15
18a + 30b = 36
....kurangkan...
7a = - 21
a = - 3

5a+ 6b = 3
5(-3) + 6b = 3
6b = 3 + 15 = 18
b = 3
.
a= -3 ---> x = 1/a = - 1/3
b = 3 ---> y = 1/b = 1/3

x+ y = -1/3  + 1/3 
x + y = 0