Question

MaryJo decided to solve the equation 3x-2= -x-6 by entering each of the expressions into her graphing calculator. To solve the equation as a system, she entered y1= 3x-2 and y2= -x-6. When she used the calculator to find the intersection, she found x= -1 and y= -5. Show the work to check to see if MaryJo found the correct solution for x to the linear equation.

Answer 1

Note that the problem states that you only need to check the solution she got for x...so we don't have to worry about y in this case. (YAY)

To verify MaryJo's answer, simply solve the equation for x:

3x - 2 = -x - 6
3x (+ x) - 2 = -x (+ x) - 6
4x - 2 = -6
4x - 2 (+ 2) = -6 (+ 2)
4x = -4
4x/4 = -4/4
x = -1

Since this conforms to MaryJo's answer, she did indeed find the correct solution for x.