precalculus
posted by ladybug on .
solve the following inequality
16(x^21) >16x
the solution set is? or there is no solution.

This problem can be solved exactly like a quadratic equation would be:
16(x^21) > 16x
16x^2  16 > 16x
16x^2  16x  16 > 0
a b c
You use the quadratic formula:
x = (b +/ sqrt(b^2  4ac))/2a 
the problem here is that after having solved the equation, you now know where the graph crosses the xaxis. You want to know where
16(x^21) > 16x
x^2  1 > x
x^2  x  1 > 0
Now from what you know about parabolas, it should clear that the graph is above the xaxis everywhere except between the roots, which you found using the method described above.