SOLUTION: solve the exponential equation: 3(x2+5x) = 1/81

Algebra ->  Equations -> SOLUTION: solve the exponential equation: 3(x2+5x) = 1/81      Log On


   

Question 368281: solve the exponential equation:
3(x2+5x) = 1/81
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
3%28x%5E2%2B5x%29+=+1%2F81
243%28x%5E2%2B5x%29+=+1
243x%5E2%2B1215x-1=0
Use the quadratic formula,
x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
x+=+%28-1215+%2B-+sqrt%28+1215%5E2-4%2A243%2A%28-1%29+%29%29%2F%282%2A243%29+
x+=+%28-1215+%2B-+sqrt%28+1476225%2B972+%29%29%2F%28486%29+
x+=+%28-1215+%2B-+sqrt%28+1477197+%29%29%2F%28486%29+
x+=+%28-1215+%2B-+9%2Asqrt%2818237++%29%29%2F%28486%29+
highlight%28x+=+%28-135+%2B-+sqrt%2818237++%29%29%2F%2854%29%29+