0.2x +
0.3y =
1.3 ;
0.4 x +
0.5 y
= 2.3
Q. Solve the following pair of linear equations by the substitution � method
Soln.
13 – 3y
2
x =
4x
+
5y
= 23
... (ii)
... (iii)
Substituting equation (iii) in equation (ii)
13 – 3y
2
4
+ 5y
= 23
+
5y
= 23
26
= 23 – 26
– 1 y
2x
+
3y
= 13
... (i)
Write this equation either �x = something
or
y = something
2
– 6y
Consider (i)
Consider any one of the two equations
Consider simpler of the two equations
2x
+
3y
= 13
= – 3
– 1 y
=
y
– 1
– 3
= 3
y
Substitute y = 3 in (iii),
=
x
=
=
= 2
x
∴ x = 2 and y = 3 is the solution of the given equations.
Lets multiply both equation by 10 to remove decimal point