college algebra
posted by alli on .
solve the following inequality. write the answer in interval notation
x^34x^221x<0
please show work so i can understand this problem better! thanks

Since x^34x^221x = x(x+3)(x7)
there are no repeated roots. So, at each root, the graph crosses the xaxis, and the function changes sign.
Starting with large negative x, all 3 factors are negative. So, on the number line, start with  signs and switch at each root:
 7 +++++ 0  3 +++++++
x is in (oo,7) U (0,3)