Question

`y=5x^3-8x` find y when x = 5

Answer 1

For this case, we have an equation of the form
`y = f (x)`, where
`f (x) = 5x ^ 3-8x`, we must replace
`x = 5` in the following equation:

`y = 5x ^ 3-8x\\y = 5 (5) ^ 3-8 (5)\\y = 5 (5 * 5 * 5) -40\\y = 5 ^ 4-40`

Solving the power:

`5 ^ 4 = 5 * 5 * 5 * 5 = 625\\y = 625-40\\y = 585`

Answer:

`For\ x = 5,\ y = 585`

Answer 2

585

Explanation:

y = 5x³ - 8x Let x = 5

= 5(5)³ - 8 × 5

= 5 × 125 – 40

= 625 – 40

= 585