Question

if 3x+7y=47 AND 2x-y=3 what is the value of x

Answer 1

Answer:

The value of x is = 4

Step-by-step explanation:

The given two equations are

3x+7y = 47 -----(1)

And 2x-y = 3 -------(2)

Now we have to solve this equation to find the value of x,

So, solving the two given equation,

(1) ×1 + (2) ×7,

Then,

3x+7y +14x -7y = 47+7×3

=> 17x = 47+21

=> 17x = 68

=> x = 68÷17 = 4

=> x = 4

So, the value of x is = 4

Answer 2

Answer:

The value of x is 4.

Step-by-step explanation:

Given algebraic expressions are

              $3x+7y=47----(1)\\ \\ 2x-y=3----(2)$

To solve a pair of equations using substitution, first we have to solve one of the equations for one of the variables. Then substituting the result for that variable in the other equation, we get

              $3x+7y=47\\ \\ 3x=47-7y\\ \\ x=\frac{47-7y}{3} ------(3)$

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

                      $2x-y=3\\ \\ 2(\frac{47-7y}{3} )-y=3\\ \\ \frac{94-14y}{3}-y=3\\ \\ \frac{94-14y-3y}{3} =3\\ \\ \frac{94-17y}{3}=3\\ \\ 94-17y=3 \cdot 3\\ \\ 94-17y=9\\ \\ 17y=94-9=85\\ \\ y=\frac{85}{17}=5$

Putting the value of y in equation (1), we get

                         $x=\frac{47-7y}{3}=\frac{47-7 \cdot 5}{3} \\ \\ x=\frac{47-35}{3}=\frac{12}{3}=4$