WAEC - Mathematics (2006 - No. 20)
If x + y = 12 and 3x - y = 20, find the value of 2x - y
8
10
12
15
Vysvětlení
x + y = 12
+ 3x - y = 20
---------------
4x = 32
x = 8
x + y = 12; 8 + y = 12; y = 12 - 8
= 4
2x - y = 2(8) - 4; 16 - 4 = 12
+ 3x - y = 20
---------------
4x = 32
x = 8
x + y = 12; 8 + y = 12; y = 12 - 8
= 4
2x - y = 2(8) - 4; 16 - 4 = 12