After staring at this for a few seconds, I think the equation
![-5√(10)\cdot√(15)=[1]√([2])](https://img.qammunity.org/2020/formulas/mathematics/middle-school/x1x12sjmrkzthzcebjb8ajbb07zura71tc.png)
is asking you to simplify the left hand side so that it has a form matching the right hand side, and [1] and [2] are placeholders. My guess is that they're supposed to be integers.
Notice that



Then multiplying by -5, we have

so I believe [1] = -25, and [2] = 6.