`a) x(x² – 2x + 5)`

`= x.x² – x.2x + x.5`
`= x³ – 2x² + 5x`

`b) 5x(x⁴ – 3x² + 5x + 2)`

`= 5x.x⁴ – 5x.3x² + 5x.5x + 5x.2`
`= 5x⁵ – 15x³ + 25x² + 10x`

`c) (–3,5x²)(2x⁴ – 3/2x² + 1)`

`= –3,5x².2x⁴ + (–3,5x²)(-3/2x²) + (–3,5x²).1`
`= –7x⁶ + 21/4x⁴ – 3,5x²`

`d) 1 3/4.x³(2x³ + x² – 2/5x + 2)`

`= 7/4x³.2x³ + 7/4x³·x² – 7/4.x³.2/5x +7/4x³.2`
`= 7/2x⁶ + 7/4x⁵ – 7/10x⁴ + 7/2x³`