document.write( "Question 1176836: . Find four rational numbers such that the product of the first, third, and fourth numbers is --6. The second number is 3 less than the first number, the third is 2 less than the second, and the fourth is 2 less than the third \n" ); document.write( "
Algebra.Com's Answer #804679 by greenestamps(13200)\"\" \"About 
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\n" ); document.write( "You can ignore one of the responses you have received, since it answers a different question than the one that is asked.

\n" ); document.write( "I would advise you also to ignore most of the response from the other tutor, who takes 20-30 steps to start with four unknowns and four equations to end up with a single equation in one unknown. That might be good exercise in algebra, but it is a huge waste of time.

\n" ); document.write( "Take the time (you don't need much) to set up the problem using a single variable:

\n" ); document.write( "1st number: x
\n" ); document.write( "2nd number: x-3 (3 less than the 1st)
\n" ); document.write( "3rd number: x-5 (2 less than the 2nd)
\n" ); document.write( "4th number: x-7 (2 less than the 3rd)

\n" ); document.write( "Given that the product of the 1st, 3rd, and 4th is -6, we have

\n" ); document.write( "\"x%28x-5%29%28x-7%29+=+-6\"

\n" ); document.write( "Solving this algebraically means finding the roots of a cubic equation, which is a lengthy process. Or you could finish solving the problem using a graphing calculator.

\n" ); document.write( "But, assuming a solution is to be obtained without a calculator, I would solve the problem from here using logical reasoning and some simple calculations.

\n" ); document.write( "The equation says the product of x, x-5, and x-7 is a negative number. Simple analysis shows that the product is negative for values of x less than 0, or between 5 and 7. Negative answers are far less likely, so we can look for an answer between 5 and 7.

\n" ); document.write( "Then, since the product is EXACTLY -6, it is very likely that the factors x, x-5, and x-7 are all whole numbers. So we try x=6 and find x(x-5)(x-7) = 6(1)(-1) = -6, as we wanted.

\n" ); document.write( "ANSWERS:
\n" ); document.write( "1st number = x = 6
\n" ); document.write( "2nd number = x-3 = 3
\n" ); document.write( "3rd number = x-5 = 1
\n" ); document.write( "4th number = x-7 = -1

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