Your question implies there are choices given with possible answers. As I do not have those in front of me, I will show you how to simplify the radical. It is likely that the answer you seek is the simplified radical.
To simplify [tex] \sqrt{50 a^{6} b^{7} } [/tex] we use the following identity: for positive values of a and b, [tex] \sqrt{ab}= \sqrt{a} \sqrt{b} [/tex]
That identity allows us to re-write what we are given as [tex] \sqrt{50} \sqrt{ a^6 } \sqrt{b^{7} [/tex]. Let us now consider each of these separately.
Though 50 is not a perfect square it can be written as 25 x 2 and 25 is a perfect square. Thus, we obtain [tex] \sqrt{50}= \sqrt{25} \sqrt{2}=5 \sqrt{2} [/tex]
Next we consider [tex] a^{6} [/tex] which is a perfect square as it is equal to [tex] (a^{3}) (a^{3}) [/tex]. Thus, [tex] \sqrt{a^{6}} = a^{3} [/tex]
Lastly, we consider [tex] b^{7} [/tex] which can be written as [tex](b^{1})( b^{6}) [/tex] and since [tex] b^{6} [/tex] is a perfect square we obtain the following: [tex] \sqrt{b ^{7} } =\sqrt{b ^{1}} \sqrt{b^6} = b^{3} \sqrt{b} [/tex]
Putting that all together we obtain [tex]\sqrt{50 a^{6} b^{7} }=25a ^{3}b ^{3} \sqrt{2b} [/tex]
