Question

solve 5x-y=8,x-2y=7 by substitution method​

Answer 1

$\huge\purple{Required \: Answer :}$

Given Equation -

$5x - y = 8 \\ x - 2y = 7$

Solution :

From Equation 2,

$x = 2y + 7$

Put ${x = 2y + 7}$ In Equation 1 ,

$5 \: ( \: 2y + 7 \: ) - y = 8 \\ 10y + 35 - y = 8 \\ 9y + 35 = 8 \\ 9y = 8 - 35 \\ 9y = - 27 \\ y = \frac{ - 27}{9} \\ y = - 3$

Put ${y = -3}$ In Equation 2 ,

$x - 2y = 7 \\ x - 2( - 3) = 7 \\ x + 6 = 7 \\ x = 7 - 6 \\ x = 1 \: \: \: \: \: \: \: \:$

$\huge{x = 1 , \: y = -3}$

$\huge{Thanks}$

Answer 2

Answer:

x = 1; y = -3.

Step-by-step explanation:

From the first equation:

y = 5x - 8

Substituting the above value of y into the second equation:

x - 2(5x - 8) = 7

=> x - 10x + 16 = 7

=> 9x = 9

=> x = 1

Putting the value of x in the above equation for y:

y = 5.1 - 8 = 5 - 8 = -3