Will H. answered • 04/16/13
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I'm assuming you need to solve for x.
With this type of expression (x + ?)(x + ?) = 0, the solutions are fairly simple. To make this easier to see, we'll call the first "?" a and the second one b, so the expression is:
(x + a)(x + b) = 0
I'm sure you already know what you get when you multiply anything by 0, right? It's clear when you substitute in 0 for the first expression in parentheses that 0 * (x + b) = 0. So here's what you do:
Assume one of the parts in parentheses is equal to zero, we'll show the first one equal to zero. So (x + a) = 0. You may have already solved this kind of equation in the past, but just in case you haven't:
x + a = 0 Subtract a from both sides of the equals sign.
x = 0 - a Remove the zero; it makes no difference to the equation.
x = -a
Solving this way gives you your first solution: x = -a. To solve for the other solution, simply repeat the steps above, setting the second expression in parentheses equal to zero, so (x + b) = 0. This will give you x = -b.
The above method solves the problem symbolically, using a and b instead of actual numbers, but you can simply replace a and b with whatever numbers are in the problem to solve for any problem of this type. It also works when you have even more expressions in parentheses, such as (x + a)(x + b)(x + c) = 0, or if the equation is not set to zero, such as (x + a)(x + b) = 5.
Have fun!
