Question

2x-7y=7,3x+y=22 solve by substitution method of 9th std practice set 5.1 Q.3

Answer 1

нєуα

нєяє ιѕ тнє αиѕωєя

gινєи єqυαтισиѕ :-

2χ - 7у = 7 ___(1)

αи∂

3χ + у = 22 ____(2)

σи fυятнєя ѕσℓνιиg (2), ωє gєт

у = 22 - 3χ ____(3)

ρυт тнιѕ ιи (1), ωє gєт

2χ - 7(22 - 3χ) = 7

2χ - 154 + 21χ = 7

23χ = 161

χ = 7

ρυт тнιѕ ιи (3), ωє gєт

у = 22 - 3(7)

у = 22 - 21

у = 1

нσρє тнιѕ нєℓρѕ.

Answer 2

Hey !!


2X - 7Y = 7 ---------(1)


And,


3X + Y = 22 ----------(2)


From equation (1) , we get



2X - 7Y = 7



2X = ( 7 + 7Y )


X = ( 7 + 7Y /2 ) ---------(3)


Putting the value of X in equation (2) , we get




3X + Y = 22



3 × ( 7 + 7Y/2 ) + Y = 22





21 + 21Y/2 + Y = 22



21 + 21Y + 2Y = 44




23Y = 44 - 21



23Y = 23


Y = 1.



Putting the value of Y in equation (3) , we get


X = ( 7 + 7Y /2 )


X = ( 7 + 7 × 1 / 2 ) = 14/2 = 7.


Hence,

X = 7 and Y = 1.