Question

Please help with this problem

Answer 1

`-√(9y^2) = -1\cdot √(9)\cdot √(y^2)`

I assume you're good with
`√(9)=3`, so this gives us:

`= -3\cdot √(y^2)`

Now the trick on the variable portion is that since y<0, when you square y, you turn it from being a negative number into a positive
`y^2` value. And when you take the square root of that, you keep the positive value. So effectively,
`√(y^2) = |y|`, since it just makes the negative number become positive.

`= -3|y|`