You can do foil method first, to make it easier and to avoid product rule,
y= 45x^4 - 15x³ + 25x² - 72x² + 24x - 40
Simplify like terms,
y= 45x^4 - 15x³ - 47x² + 24x - 40
Now, find derivative,
dy/dx = 180x³ - 45x² - 94x + 24
It's very easy, just try raising 5 to different powers until you get 125.
5^1 = 5
5^2 = 5*5 = 25
5^3 = 25*5 = 125
Ah, x is 3!
Would it be X=Y^3-2 bc I think you flip the x and y
C is the answer all you had to do was
31.80-4.00
Which is 27.80
Then add 2.50
Which is 30.3!
