Question

3) By elimination method of variable. Solve the simultaneous equations. 5x + 2y = 9; 4x - y = 15.​

Answer 1

Answer:

x = 3, y = -3

Step-by-step explanation:

Given 2 equations:

5x + 2y = 9 (i) and

4x - y = 15 (ii)

Multiplying (ii) by 2, we get:

8x - 2y = 30 (iii)

Adding (i) and (iii), we get:

13x = 39

x = 3

Plugging x = 3 in (ii), we get:

12 - y = 15

y = -3

Answer 2

Answer:

The solution to the given problem is$x=3 \ and\ y =-3$.

Step-by-step explanation:

Given: $5x + 2y = 9; 4x - y = 15$

We have to solve the above simultaneous equations.

• As we know, the elimination method is the process of eliminating one of the variables in the system of linear equations using addition or subtraction methods in conjunction with multiplication or division of coefficients of the variables.

We are solving in the following way:

We have,

$5x + 2y = 9; 4x - y = 15$

let assume,

$5x + 2y = 9\ \ ....1)\\ 4x - y = 15\ \ ....2)$

multiplying eq.2) by 2 we get:

$=>8x-2y=30\ \ ....3)$

Adding eq.1) and 3)

$5x +8x+2y+(-2y)=9+30\\=>13x+2y-2y=39\\=>13x=39\\\\=>x=\frac{39}{13} \\\\=>x=3$

Hence, the value of x will be 3.

Now we will put this value of x in the eq.2)

$4x - y = 15$

$=>4\times3-y=15\\=>12-y=15\\=>-y=15-12\\=>-y=3\\=>y=-3$

Hence, we get;

$x=3 \ and\ y =-3$