Possible Duplicate:
How to factor quadratic $ax^2+bx+c$?
If $x^2 + 2x - 35 = 0$, then $x = $?
Possible Duplicate:
How to factor quadratic $ax^2+bx+c$?
If $x^2 + 2x - 35 = 0$, then $x = $?
Well you can do this: Observe that $7 \times 5 =35$ and the difference between $7$ and $5$ is $2$, so you can write your equation as $x^{2}+7x - 5x -35=0$ which then can be written as $(x+7)\cdot (x-5)$.
This is a quadratic equation. Try completing the square.
FWIW:
Since one side of the equation is already zero, you use that $AB = 0 \Longrightarrow A = 0 \text{ or } B = 0.$ This reduces your problem to factoring the left hand side of the equation.
In general, when factoring monic quadratic polynomials, i.e., expressions of the form $x^2 + bx + c$, one wants to find two numbers that add to $b$ and multiply to $c$. In your case the numbers that add to $2$ and multiply to $-35$ are the numbers $7$ and $-2$. So,
$x^2 + 2x - 35 = (x+7)(x-5).$
Now, $(x+7)(x-5) = 0 \Longrightarrow (x + 7) = 0$ or $(x - 5) = 0$. This gives $x = -7$ or $x = 5$.