Question

Tolong bantu no 18,19,26,27
pakai cara eliminasi ,,please tolong dibantu
untuk nambah poin dan pahala :)

Answer 1

18.
3x-2y = 12 | x3| 9x-6y = 36
4x-3y = 7   | x2| 8x-6y = 14
______________________  -
x = 22; 3(22)-2y = 12 => -2y = 66-12
y = -54/-2 = 27

19. 
...(1) 4x-5y = 13 |x3| 12x-15y = 39
...(2) 5x+3y = 7  |x5| 25x+15y = 35
_____________________________ +
37x = 74
x = 2
sub. ...(2)
5(2) + 3y = 7
3y = 7 - 10
y = -1 ==> 3(2) + 4(-1) = 6 - 4 = 2

26.
...(1) 4x-3y = 15    |x2| 8x-6y = 30
...(2) -3x+2y = -12 |x3|-9x+6y = -36
____________________________+
-x = -6
x = 6

sub. ...(2)
-3(6)+2y = -12
2y = -12+18
y = 6/2 = 3
x = m; y = n
2(6) - 6(3) = 12-18 = -6 (B)

27.
ax + by = 2
...(1) 2a + b = 2   |x5| 10a+5b = 10
...(2) -6a - 5b = 2 |x1| -6a - 5b = 2
_______________________+
4a = 8 | sub ...(1)
a = 2   | 2(2) + b = 2
b = 2-4 = -2 (A)