SIMULTANEOUS EQUATIONS 1

Solve the following equations by substitution method.

3x - y = 11

x + 3y = 27

Solution

3x - y = 11 ----------- (i)

x + 3y = 27 ---------- (ii)

From equation (i)

3x - y = 11

3x - 11 = y

∴ y = 3x - 11 ----------(iii)

substitute equation (iii) in (ii) above,

x + 3(3x – 11 ) = 27

x + 9x – 33  = 27

x  + 9x  = 27 + 33

 10x  = 60                  [since x+9x=10x and 27+33=60]

10x  = 60

                  

10x = 60

10      10

x = 6

From equation (iii)

y = 3x - 11 ----------(iii)

y = 3(6) – 11

y = 18 – 11

y = 7

Hence x=6 and y=7.

TRY THIS………………………..

Solve the following equations by substitution method.

x + y = 11

2x - y = 4