Which exponential expression is equivalent to $$^8\sqrt{z^{7}}$$ ?

<div id="id_cont_display" class="markdown-body editormd-html-preview"><textarea>Which exponential expression is equivalent to $$^8\sqrt{z^{7}}$$ ?</textarea>Which exponential expression is equivalent to <math><semantics><mrow><msup><mrow></mrow><mn>8</mn></msup><msqrt><mrow><msup><mi>z</mi><mrow><mn>7</mn></mrow></msup></mrow></msqrt></mrow><annotation encoding="application/x-tex">^8\sqrt{z^{7}}</annotation></semantics></math>​8​​√​z​7​​​​​ ?
</div>