Find the intervals $on$ which $f(x)is$ increasing and the intervals $on$ which $f(x)is$ decreasing. Then sketch the graph. Add horizontal tangent lines.

$f(x)=2x^4-100x^2$

Compute the derivative $off(x).$

$f^{\text{'}}(x)=$

Select the correct choice below and, $if$ necessary, fill $in$ the answer box $to$ complete your choice.

$A.$ The function $is$ increasing $on$

$(Type$ your answer using interval notation. Use a comma $to$ separate answers $as$ needed.$)$

$B.$ The function $is$ never increasing.