Since the constant 10 is -10 this tells us we are going to have different signs + - after you have factored the equation.
First thing first. Think of two numbers that will give you the product(The answer after two numbers are multiplied) of -10 and the sum(Two numbers added together) of +3. I get the 3 from the 3x.
We know 5 x -2 = -10 and the sum 5 + -2 = +3 With that said, we found our two factors (x + 5)(x - 2)
Now write them as zeros and solve for x x + 5 = 0 x = -5