Q:

Use the definition of the derivative to find the derivative of 𝑦 = 12π‘₯ 2 + 5.

Accepted Solution

A:
The definition of the derivative of a function 𝑓(π‘₯) is given by: 𝑓′(π‘₯) = lim_(h β†’ 0) [𝑓(π‘₯ + h) βˆ’ 𝑓(π‘₯)]/h To find the derivative of 𝑦 = 12π‘₯^2 + 5, we need to apply this formula: 𝑦′(π‘₯) = lim_(h β†’ 0) [𝑦(π‘₯ + h) βˆ’ 𝑦(π‘₯)]/h First, we need to find 𝑦(π‘₯ + h) and 𝑦(π‘₯): 𝑦(π‘₯ + h) = 12(π‘₯ + h)^2 + 5 𝑦(π‘₯) = 12π‘₯^2 + 5 Next, we can substitute these expressions into the formula: 𝑦′(π‘₯) = lim_(h β†’ 0) [12(π‘₯ + h)^2 + 5 βˆ’ (12π‘₯^2 + 5)]/h Expanding the square, we get: 𝑦′(π‘₯) = lim_(h β†’ 0) [12(π‘₯^2 + 2π‘₯h + h^2) + 5 βˆ’ 12π‘₯^2 βˆ’ 5]/h Simplifying, we get: 𝑦′(π‘₯) = lim_(h β†’ 0) [24π‘₯h + 12h^2]/h Canceling out the factor of h in the numerator and denominator, we get: 𝑦′(π‘₯) = lim_(h β†’ 0) (24π‘₯ + 12h) Taking the limit as h approaches 0, we get: 𝑦′(π‘₯) = 24π‘₯ Therefore, the derivative of 𝑦 = 12π‘₯^2 + 5 is 𝑦′(π‘₯) = 24π‘₯.