2x+3y= 11 5x-3y= -39. nilai (7a+b) adalah

2x + 3y = 11
5x - 3y = -39
--------------------- +
7x = -28
x = -28/7
x = -4

2x + 3y = 11
2(-4) + 3y = 11
-8 + 3y = 11
3y = 11 + 8
3y = 19
y = 19/3

x = a
y = b
7a + b
= 7(-4) + 19/3
= -28 + 19/3
= -84/3 + 19/3
= -65/3
= -21 2/3

Jawab:
_______
KITA MISALKAN
=> x = a
=> y = b

METODE CAMPURAN
__________________
=> ELIMINASI DAN SUBSTITUSI

2x+3y= 11
5x-3y= -39
________ +
2x + 5x = 11 + (-39)
2x + 5x = 11 - 39
2x + 5x = -28
7x = -28
x = -28 / 7
x = -4

Kita substitusikan nilai "x" yang sudah di ketahui ke persamaan 2x+3y= 11
MAKA :
2x+3y. = 11
2(-4)+3y = 11
-8 + 3y = 11
3y = 11 + 8
3y = 19
y = 19/3

SEHINGGA NILAI
7a + b = 7 (-4) + 19/3
= -28 + 19/3
= -28 x 3/3 + 19/3
= -84/3 + 19/3
= -84 + 19 /3
= -65/3 pecahan biasa
= -21 2/3 pecahan campuran
= -21,66 pecahan desimal

*TERIMA KASIH*