ImmanuelSinaganomor 6) x + y = 6 ===========> (1) x = 6 - y 2x + y = 9 ===========> (2) 2(6 - y) + y = 9 12 - 2y + y = 9 12 - y = 9 y = 12 - 9 y = 3 x = 6 - y x = 6 - 3 x = 3 =============> A.
untuk nomor 7) x + 2y = 10 ===========> (1) x = 10 - 2y 2x + y = 8 =========> (2) 2(10 - 2y) + y = 8 20 - 4y + y = 8 20 - 3y = 8 20 - 8 = 3y 12 = 3y 12 : 3 = y y = 4 x = 10 - 2y x = 10 - 2(4) x = 10 - 8 x = 2 ============> C.
untuk nomor 8) 2x + 3y = 17 =============> (1) kali dengan 2 3x + 2y = 13 =============> (2) kali dengan 3
x + y = 6 ===========> (1)
x = 6 - y
2x + y = 9 ===========> (2)
2(6 - y) + y = 9
12 - 2y + y = 9
12 - y = 9
y = 12 - 9
y = 3
x = 6 - y
x = 6 - 3
x = 3 =============> A.
untuk nomor 7)
x + 2y = 10 ===========> (1)
x = 10 - 2y
2x + y = 8 =========> (2)
2(10 - 2y) + y = 8
20 - 4y + y = 8
20 - 3y = 8
20 - 8 = 3y
12 = 3y
12 : 3 = y
y = 4
x = 10 - 2y
x = 10 - 2(4)
x = 10 - 8
x = 2 ============> C.
untuk nomor 8)
2x + 3y = 17 =============> (1) kali dengan 2
3x + 2y = 13 =============> (2) kali dengan 3
4x + 6y = 34 ============> (1)
9x + 6y = 39 _
-5x = -5
x = 1
subsitusikan nilai x , untuk mencari nilai y
4x + 6y = 34
4(1) + 6y = 34
6y = 34 - 4
y = 30 : 6
y = 5 =============> B.
untuk nomor 9)
misalkan x dan y
x + y = 40
x - y = 8 ===========> C.