Question

Solve the system of equations.
y = x2 + 3x - 4
y= 2x - 4

Answer 1

The two solutions are

(0,-4) and (-1,-6)

Explanation:

The ys have to be equal so you can equate the right hand side.

x^2 + 3x - 4 = 2x - 4 Add 4 to both sides

x^2 + 3x = 2x Subtract 2x from both sides

x^2 + 3x - 2x = 0 Combine

x^2 + x = 0 Factor

x(x + 1) =0

Just to show you that these two points really are the solutions, you can see the graph below

x has 2 values

x + 1 = 0

x = - 1

or

x = 0

Now solve for y

y = 2x - 4

Let x = 0

y = - 4

Let x = - 1

y = 2x - 4

y = -2 - 4

y = - 6

The blue is y = x^2 + 3x - 4

The green line is y = 2x - 4