Q 348 - Intermediate Algebra

Question

In the following exercises, decide whether it would be more convenient to solve the system of equations by substitution or elimination.  

$\left\{\begin{array}{l}y=3x-9\\ 4x-5y=23\end{array}\right.$

Step-by-Step Solution

Answer

It would be more convenient to solve the system of equations  $\left\{\begin{array}{l}y=3x-9\\ 4x-5y=23\end{array}\right.$ by the substitution method.

Step 1. Given Information

Consider a system of equations $\left\{\begin{array}{l}y=3x-9\\ 4x-5y=23\end{array}\right.$

We need to know which method will be more convenient to solve the system of equations. 

Step 2. Choosing the most convenient method

In the given system of equations $\left\{\begin{array}{l}y=3x-9\\ 4x-5y=23\end{array}\right.$, the first equation is already solved for $y$. So it will be more convenient to use the substitution method.

We can use the first equation and substitute the value of $y$ in the second equation and solve for $x$. Then using the found value we can found the corresponding $y$ value.