Hello!
To solve this radical, we would need to know our perfect squares. Perfect squares are numbers multiplied by itself. Some examples are: 2 × 2 = 4, 7 × 7 = 49, 9 × 9 = 81, 6 × 6 = 36, etc.
Since 36 is a perfect square, the square root of 36 is 6. Our next step would be to multiply -7 and 6 together because the expression, -7√36 is equal to -7 × √36.
-7 × 6 = -42
Therefore, the final answer is -42.