Beginning with the quadratic equation y=ax to the power of 2 + bx+c , fred calculated -b/2a and then plugged that number in for x to get a y. what is one reason he might have done this?

While scuba diving, rajeev dove to a depth of 12.6 feet below the surface of the water and then descended another 8.7 feet. what expression can be used to find rajeev's new position? 12.6 – 8.7 –12.6 – 8.7 –12.6 – (–8.7) 12.6 – (–8.7)

Me because some of question i don’t understand

If f(x) = x+8 and g(x) = 4x- 3, find (f+g)(x)