Final answer:
To make the equation valid, the expression that will replace the ? is 3(4x+7)².
Step-by-step explanation:
To make the equation valid, we need to find the expression that is equal to the left side of the equation. The given equation is (d)/(dx)(4x+7)³ = 3(4x+7)². To find the expression that will make the equation valid, we can simplify the left side of the equation. Taking the derivative of (4x+7)³, we get 3(4x+7)². Therefore, the expression that will make the equation valid is 3(4x+7)².