sistem persamaan 7x+2y=19 dan 4x-3y=15 nilai dari3x-2y adalah

7x + 2y = 19
4x - 3y = 15
= 3 × 7x + 3 × 2y = 3× 19
2 × 4x - 2 × 3y = 2 × 15
= 21x + 6y = 57
8x - 6y = 30
= 21x + 6y + 8x - 6y = 57 + 30
= 29x = 87
= 29x ÷ 29 = 87 ÷ 29
= x = 3
= 4 × 3 - 3y = 15
= 12 - 3y = 15
= -3y = 15 - 12
= -3y = 3
= y = -1
= (x , y)=(3 , -1)
= 7 × 3 + 2 × ( -1 ) = 19
4 × 3 - 3 × ( -1 ) = 15
= 19 = 19
15 = 15
= ( x , y )=( 3 , -1 )