document.write( "Question 294621: x(x+3)= 18 \n" ); document.write( "

Algebra.Com's Answer #212413 by Monkibat(7) $\"\"$ $\"About$

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First distribute the x to (x+3). $\"x%28x%2B3%29\"$ , x times x = $\"x%5E2\"$ and x times 3 = 3x. Now we have $\"x%5E2%2B3x=18\"$ . Now set the equation to zero by subtracting both sides by 18. Now we have the equation: $\"x%5E2%2B3x-18=0\"$ . Now we can factor the equation. We have to find factors of -18 that add to +3. Positive 6 and negative 3 are factors that work. $\"x%5E2%2B3x-18=0\"$ factors to $\"%28x%2B6%29%28x-3%29=0\"$ . Now set each equation to zero and solve. $\"x%2B6=0\"$ , subtract 6 from both sides, $\"x=-6\"$ . Now $\"x-3=0\"$ , add 3 to both sides, $\"x=3\"$ . The answers are $\"x=-6\"$ and $\"x=3\"$ . We're not done, we have to check to make sure both solutions work. Plug -6 into the original equation $\"x%28x%2B3%29=18\"$ , $\"-6%28-6%2B3%29=18\"$ = $\"-6%28-3%29=18\"$ = $\"18=18\"$ . Therefore $\"x=-6\"$ works and is one of your answers, now we have to check $\"x=3\"$ by plugging 3 into the original equation. $\"3%283%2B3%29=18\"$ = $\"3%286%29=18\"$ = $\"18=18\"$ . Therefore $\"x=3\"$ works and is one of the solutions too. -6 and 3 are you answers. \n" ); document.write( "

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