Question

solve with substitution method
4x + 3y = 5
3x - 2y = 8
​

Answer 1

Answer:

$4x + 3y = 5 - - - - (1) \\ \\ 3x - 2y = 8 - - - - - - (2) \\ \\ then \: from \: eqn \: (2) \\ 3x - 2y = 8 \\ = > 3x = 8 + 2y \\ = > x = \frac{8 + 2y}{3} \\ putting \: the \: value \: of \: x \: in \: eqn \: (1) \\ 4( \frac{8 + 2y}{3} ) + 3y = 5 \\ = > \frac{32 + 8y}{3} + 3y = 5 \\ = > \frac{32 + 8y + 9y}{3} = 5 \\ = > 32 + 17y = 15 \\ = > 17y = - 17 \\ = > y = - 1 \\ putting \: the \: value \: of \: y \: in \: eqn \: (1) \\ 4x + 3( - 1) = 5 \\ = > 4x - 3 = 5 \\ = > 4x = 8 \\ = > x = 2$

so x = 2 ,y = -1

Answer 2

Given :

• 4x + 3y = 5 .....(1)
• 3x - 2y = 8 ......(2)

Solution:

In equation 2,

→ 3x - 2y = 8

→ 3x = 8 + 2y

=> x = (8 + 2y)/3

Putting this value in equation 1,

we get,

→ 4[(8 + 2y)/3] + 3y = 5

→ (32 + 8y)/3 + 3y = 5

→ (32 + 8y + 9y)/3 = 5

→ (32 + 17y)/3 = 5

→ 15 = 32 + 17y

→ 15 - 32 = 17y

→ -17y = 17y

=> y = - 1

putting this value in equation 1,

→ 4x + 3(-1) = 5

→ 4x - 3 = 5

→ 4x = 5 + 3

→ 4x = 8

→ x = 8/4

=> x = 2