Free ACT Practice Question

If for all positive integers $m$, $[m] = -\lvert\sqrt{m}\rvert$ when $m$ is odd and $[m] = -\sqrt{m}$ when $m$ is even; and for all negative integers $m$, $[m] = m^2$ when $m$ is odd and $[m] = -\lvert m^2\rvert$ when $m$ is even, what is the value of \[ \frac{[49]^4 \times [-4]}{[-49] \times [4]}\,? \]