1) 5x + 2y = 11 - (1)
x + y = 4 - (2)
From (2),
x = 4 - y - (3)
Substitute (3) into (1),
5(4 - y) + 2y = 11
20 - 5y + 2y = 11
20 - 3y = 11
20 - 11 = 3y
9 = 3y
3 = y
Substitute y = 3 into (2),
x + 3 = 4
x = 4 - 3
= 1
Therefore, x = 1, y = 3
OR
5x + 2y = 11 - (1)
x + y = 4 - (2)
(2) X 2: 2x + 2y = 8 - (3)
(1) - (3): 3x = 3
x = 1
Substitute x = 1 into (2),
1 + y = 4
y = 4 - 1
= 3
Therefore, x = 1, y = 3
2) LHS = RHS. Unless you are at higher level, this is not
possible.
3) Same as question 2.
