SOLUTION: 3x^-2 - 7x^-1 - 6 = 0 this one has got me stumped

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Question 495518: 3x^-2 - 7x^-1 - 6 = 0
this one has got me stumped
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
+3x%5E%28-2%29+-+7x%5E%28-1%29+-+6+=+0+
+3x%5E%28-2%29+-+7x%5E%28-1%29+=+6+
+3%2Fx%5E2++-++7%2Fx+=+6+
Multiply both sides by +x%5E2+
+3+-+7x+=+6x%5E2+
+6x%5E2+%2B+7x+-+3+=+0+
Use the quadratic formula
+x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
+a+=+6+
+b+=+7+
+c+=+-3+
+x+=+%28-7+%2B-+sqrt%28+7%5E2-4%2A6%2A%28-3%29+%29%29%2F%282%2A6%29+
+x+=+%28-7+%2B-+sqrt%28+49+%2B+72+%29%29+%2F+12+
+x+=+%28-7+%2B-+sqrt%28+121+%29%29+%2F+12+
+x+=+%28+-7+%2B+11+%29+%2F+12+
+x+=+1%2F3+
and
+x+=+%28-7+-+11+%29+%2F+12+
+x+=+-3%2F2+
------------
check answers:
+3x%5E%28-2%29+-+7x%5E%28-1%29+-+6+=+0+
+3%2A%281%2F3%29%5E%28-2%29+-+7%2A%281%2F3%29%5E%28-1%29+-+6+=+0+
+3%2A9+-+7%2A3+-+6+=+0+
+27+-+21+-+6+=+0+
+6+-+6+=+0+
OK
+3%28-3%2F2%29%5E%28-2%29+-+7%2A%28-3%2F2%29%5E%28-1%29+-+6+=+0+
+3%2A%284%2F9%29++%2B+7%2A%282%2F3%29+-+6+=+0+
+3%2A%284%2F9%29+%2B+7%2A%286%2F9%29+-+54%2F9+=+0+
+%281%2F9%29%2A%28+12+%2B+42+-+54+%29+=+0+
+%281%2F9%29%2A%28+54+-+54+%29+=+0+
OK