Question

Solve the following simultaneous equations: 2x - 3y = 10 ; 4x - 5y = 15

Answer 1

Step-by-step explanation:

2x-3y=10 --------eq.no.1

multiplying by 2

4x-6y=20 ---------eq.no. 2

4x-5y=15-----------eq.no.3

Substracting eq.no. 2 and 1

4x-6y=20

- 4x-5y=15

_________

0x+y=5

therefore ,y=5

Put y=5 in eq.no.1

2x-3y=10

therefore,

2x-15=10

2x=10+15=25

x=25/2

x=12.5

[hence ,x=12.5 and y=5]

Answer 2

Answer:

x= - 5 / 2

y= - 5

Step-by-step explanation:

2 x - 3 y= 1 0

or, 2 x= 10 + 3 y

or, x=(10 + 3 y) ÷ 2 .(1)

n o w, 4 x - 5 y= 15

or, 4 { ( 10 + 3 y) ÷ 2 } - 5 y = 15

or, 2(10 + 3 y) - 5 y = 15

or, 20 + 6 y - 5 y = 15

or, 20 + y = 15

or, y = 15 - 20

s o, y = -5

n o w, p l a c i n g y = - 5 in no. (1)

we g e t, x = (10 + 3 . - 5) ÷ 2

or, x = 10 - 15 ÷ 2

or, x = - 5 ÷ 2

s o, x = - 5 / 2

hope it helps