To solve, you must make one side of the equation equal to zero. We can do this by subtracting 3x on both sides of the equation.
x^2 + 7x = 3x
- 3x -3x
x^2 + 4x = 0.
Then we substitute the equation into the quadratic equation.
[tex] \frac{-b+- \sqrt{b^2-4ac} }{2a} [/tex]
Where a = 1 b = 4 and c = 0
[tex] \frac{-(4)+- \sqrt{(4)^2-4(1)(0)} }{2(1)} [/tex]
We first solve whats inside the square root.
[tex] \frac{-(4)+- \sqrt{16} }{2(1)} [/tex]
[tex] \sqrt{16} = 4[/tex]
Now we solve for -4 and 4.
[tex]-4 - 4 = -8[/tex]
[tex]-4+4=0[/tex]
Then divide both answer by 2
[tex] \frac{-8}{2} = -4[/tex]
The division of any by zero is zero
So the answer are x = -4 and x = 0
