Question

2. Решить систему способом подстановки:3х+у=79х-4у=-7​

Answer 1

Харлвмылвиовочгрврсрчовисоивов

Answer 2

Solving the System of Equations by Substitution

To solve the system of equations \(3x + y = 7\) and \(x - 4y = -7\) using the method of substitution, we can solve one equation for one variable and then substitute that expression into the other equation.

First, let's solve the second equation for \(x\): \[x = 4y - 7\]

Now, we can substitute this expression for \(x\) into the first equation: \[3(4y - 7) + y = 7\]

Solving for \(y\): \[12y - 21 + y = 7\] \[13y - 21 = 7\] \[13y = 28\] \[y = \frac{28}{13}\]

Now that we have found the value of \(y\), we can substitute it back into the equation \(x = 4y - 7\) to find the value of \(x\): \[x = 4\left(\frac{28}{13}\right) - 7\] \[x = \frac{112}{13} - 7\] \[x = \frac{112}{13} - \frac{91}{13}\] \[x = \frac{21}{13}\]

Solution

So, the solution to the system of equations is: x = 21/13 y = 28/13