Sagot :
5x+2y=11 x4
4x-3y=18 x5
20x+8y=44
20x-15y=90
23y= -46
y= -46/23 = -2
5x+2*-2=11
5x-4=11
5x=15
x=3
4x-3y=18 x5
20x+8y=44
20x-15y=90
23y= -46
y= -46/23 = -2
5x+2*-2=11
5x-4=11
5x=15
x=3
(1) 5x + 2y = 11
(2) 4x - 3y = 18
Multiply (1) by 4
Multiply (2) by 5
This gives equation (3) and (4)
(3) 20x + 8y = 44
(4) 20x - 15y = 90
(3) - (4)
23y = -46
-46
y = -------- = -2
23
Substitute y into equation (2)
4x - 3(-2) = 18
4x + 6 = 18
4x = 12
x = 3
(2) 4x - 3y = 18
Multiply (1) by 4
Multiply (2) by 5
This gives equation (3) and (4)
(3) 20x + 8y = 44
(4) 20x - 15y = 90
(3) - (4)
23y = -46
-46
y = -------- = -2
23
Substitute y into equation (2)
4x - 3(-2) = 18
4x + 6 = 18
4x = 12
x = 3