Question

8x+5y=9. , 3x +2y=4 ​

Answer 1

Question:-

Find the value of x and y from the following equation:-

8x + 5y =9 , 3x + 2y = 4

Solution:-

= $\sf{8x + 5y = 9 \: -----------> (i)}$

= $\sf{3x + 2y = 4 \: -----------> (ii)}$

From eq.(i)

$\sf{8x + 5y = 9}$

= $\sf{8x = 9 - 5y}$

=> $\sf{x = \dfrac{9-5y}{8}}$

Substituting the value of x in eq. (ii)

= $\sf{3x + 5y = 9}$

=> $\sf{3\times\dfrac{(9-5y)}{8} + 2y = 4}$

=> $\sf{\dfrac{27-15y}{8}+2y = 4}$

=> $\sf{\dfrac{27-15y+16y}{8} = 4}$

=> $\sf{27+y = 8\times4}$

=> $\sf{27 + y = 32}$

=> $\sf{y = 32 - 27}$

=> $\sf{y = 5}$

Now, Putting the value of y in eq. (i)

$\sf{8x+5y = 9}$

= $\sf{8x + 5\times5 = 9}$

=> $\sf{8x + 25 = 9 }$

=> $\sf{8x = 9 - 25}$

=> $\sf{8x = -16}$

=> $\sf{x = \dfrac{-16}{8}}$

=> $\sf{x = -2}$

Therefore,

x = -2 and y = 5

Answer 2

Answer:

8x+5y=9......(1)

3x+2y=4......(2)

multiply (1)by 2

16x+10y=18......(3)

multiply ...(2) by 5

15x+10y=20.....(4)

subtracting equation ...(3) from (4)

15x+10y=20

- 16x+10y=18

-1x. =2

x= -2

put x=-2 in eqn 2

3*-2+2y=4

-6+2y=4

2y=4+6

2y=10

y=5

x= -2,y=10

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