Answer:
x = -4 and x = 5
Step-by-step explanation:
Since [tex]x^2 + 2x[/tex] and [tex]3x + 20[/tex] both equal to y, we know that the expressions equal to each other. We can write a new equation base on that.
[tex]x^2 + 2x = 3x + 20[/tex]
Now we solve the equation.
[tex]x^2 + 2x = 3x + 20[/tex]
[tex]x^2 - x = 20[/tex]
[tex]x^2 - x - 20 = 0[/tex]
[tex](x + 4) (x - 5) = 0[/tex]
[tex]x + 4 = 0 ; x -5 = 0[/tex]
[tex]x = -4 ; x = 5[/tex]
