We know that 12 = 3·4, so we can match values to the factors in the above equation to get ...
... x = 3
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You can solve by factoring, completing the square, graphing, the quadratic formula, or any other means you might devise to find that the solutions to the equation x² +x -12 = 0 are x = -4 and x = 3. In a geometry problem where x is a length, the solution x = -4 is extraneous.
Step-by-step explanation: I'm in college so I think I am capable of answering a middle school question thank you very much, and make sure to mar me brainliest.