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Find 'K' (Posted on 2006-05-15) Difficulty: 3 of 5
The product of two of the four roots of the equation x418x3+Kx2+200x1984=0 is 32. Find the value of K.

No Solution Yet Submitted by Ravi Raja    
Rating: 3.0000 (1 votes)

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Solution Comment 3 of 3 |

We are given that the product of the two roots are -32, so I started looking at the different possibilities. -8 * 4, 8*-4, -16 * 2, 16 * -2, -32 * 1, and 32 * -1.

First I plugged x=8 into the equation and got that

64K=-5504.

So K=-86.

Then I checked its pair, x=-4.  Plugging this in I got

16K=-1376.

So K=-86.

Since both x=8 and x=-4 give the same K value, K=-86 is the solution.


  Posted by Becky on 2006-05-17 14:57:15
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