Question

2x-3y=10;4×-5y=15 by elimination method ​

Answer 1

Answer:

) x + y =5 and 2x –3y = 4

By elimination method

x + y =5 ... (i)

2x –3y = 4 ... (ii)

Multiplying equation (i) by (ii), we get

2x + 2y = 10 ... (iii)

2x –3y = 4 ... (ii)

Subtracting equation (ii) from equation (iii), we get

5y = 6

y = 6/5

Putting the value in equation (i), we get

x = 5 - (6/5) = 19/5

Hence, x = 19/5 and y = 6/5

Answer 2

Given

• Two equations :-
• 2x - 3y = 10
• 4x - 5y = 15

To find

• The value of x and y by elimination method

Concept

Steps to find a value by elimination method :-

1. Make one of the digits of the variable same in both of the equations.
2. Make the signs of the variables opposite to each other.
3. As the signs will be opposite to each other, they will get cancelled and from there we will get the value of one variable.
4. Substitute the value of the variable we have got in any of the equation, from there we will get the other variable's value.

Solution

• 2x - 3y = 10 -----(1)

• 4x - 5y = 15 ------(2)

$\mapsto$ (2x - 3y = 10) × 2

$\mapsto$ 4x - 6y = 20

$\mapsto$ (4x - 5y = 15) × 1

$\mapsto$ 4x - 5y = 15

$\cancel{4x}$ - 6y = 20

$\cancel{4x}$ - 5y = 15

- ㅤㅤ+ ㅤㅤㅤ-

__________

- 1y = 5

__________

$\mapsto$ - 1y = 5

$\mapsto$ y = - 5

∴The value of y = - 5

Substituting the value of y in (1)

$\mapsto$ 2x - 3y = 10

$\mapsto$ 2x - 3(-5) = 10

$\mapsto$ 2x + 15 = 10

$\mapsto$ 2x = 10 - 15

$\mapsto$ 2x = - 5

$\mapsto$ x = -5/2

$\mapsto$ x = - 2.5

∴The value of x = -2.5