Giải thích các bước giải:
`1)`
`(x + 3)^4`
`= (x + 3)^2 . (x + 3)^2`
`= (x^2 + 6x + 9)(x^2 + 6x + 9)`
`= x^4 + 6x^3 + 9x^2 + 6x^3 + 36x^2 + 54x + 9x^2 + 54x + 81`
`= x^4 + 12x^3 + 18x^2 + 108x + 81`
`2)`
`(2x + 3)^5`
`= (2x + 3)^2 . (2x + 3)^3`
`= (4x^2 + 12x + 9)(8x^3 + 36x^2 + 54x + 27)`
`= 32x^5 + 144x^4 + 216x^3 + 108x^2 + 96x^4 + 432x^3 + 648x^2 + 324x + 72x^3 + 324x^2 + 486x + 243`
`= 32x^5 + 240x^4 + 720x^3 + 1080x^2 + 108x + 243`