Chapter 6.3, Problem 29PPE

To determine

To calculate: describe and correct the error made in the part of the solution.

Answer to Problem 29PPE

  $x=6,y=-7$

Explanation of Solution

Given information:

  $\begin{array}{l}5x+4y=2\\ 3x+3y=-3\end{array}$

Calculation:

Student has multiplied first equation with 3 and second equation with 4, and subtracted second equation from the first one to eliminate $y$ , But he/she forgot to multiply constant of second equation, i.e. -3. So that’s the mistake.

Now, let’s correct that mistake

  $15x+12y=6$

  $\_1\underset{\_}{2x+12y=-12}$

  $3x=18$

  $\therefore x=6$

  $\therefore y=-7$ (from the first equation)