We want to know what d would be when x = -1, so we can start off by plugging in -1 for x to get the following equation: . On the left hand side, 2 negatives become a positive sign, so the -(-1) becomes a +1, and 8+1 would equal 9. On the right hand side, we just multiply 2 and -1 to get -2. So, the equation now looks like this: . We know that = 3, so we would get 3 = d-2. THen we would add 2 to both sides to get d = 5. Hope this helps!
