Question

solve the following simultaneous equation x + y = 4 , 2x - 5y = 1​

Answer 1

x+y=4-------(1)
2x-5y=1-----(2)

mutplying equation no.1 by5
5x+5y=20----(3)

adding equation no.2 and 3
2x-5y=1
5x+5y=20
--------------
7x=21
x=3

put x=3 in equation no.1
3+y=4
y=4-3
y=1

(x,y)=(3,1) is the soln of given problem.

Answer 2

X + Y = 4 ..... (1)

2x - 5y = 1 ..,......(2)

multiply the equation (1) by 5 then we get

5x + 5y = 20 ....... (3)

Add the equation (2) from equation (3) then we get

7x + 0y = 21

x = 21÷7

x = 3

substitute the value x = 3 in the equation (3)

5x + 5y = 20

5(3) + 5y = 20

15 + 5y = 20

5y = 20 -15

5y = 5

y = 1

the value of x =3 and Y = 1