Question

Diketahui sistem peesamaan 7x + 2y = 11 dan 4x - 6y = 42 nilai x + y =

Answer 1

7x + 2y = 11      (x 3)     21x + 6y = 33
4x - 6 y = 42      (x1)       4x - 6y = 42
                                    ___________ +
                                         25x   = 75  -----> x= 3 ; y= -5
x+y = 3 + (-5)
       = -2

Answer 2

7x + 2y = 11 * 3
4x - 6y = 42 * 1
21 x + 6y = 33
4x - 6y = 42
___________+
25 x = 75
x = 75/25
=3
7x + 2y =11
7*3 + 2y = 11
21 + 2x = 11
2x = 11-21
2x= -10
x=-10/2
x=-5
x+y = 3 + (-5)
= -2