Toán giúp mình với $3x^{n}$ ($6x^{n-3}$ +1)- $2x^{n}$ ($9x^{n-3}$ – 1) 06/07/2021 By Brielle giúp mình với $3x^{n}$ ($6x^{n-3}$ +1)- $2x^{n}$ ($9x^{n-3}$ – 1)
`3x^n(6x^(n – 3) + 1) – 2x^n(9x^(n – 3) – 1)` `= 3x^n. 6x^(n – 3) + 3x^n – 2x^n. 9x^(n – 3) + 2x^n` `= (3. 6). (x^n. x^(n – 3)) – (2. 9). (x^n. x^(n – 3)) + (3x^n + 2x^n)` `= 18. x^(n + n – 3) – 18. x^(n + n – 3) + 5^n``= 18x^(2n – 3) – 18x^(2n – 3) + 5^n` `= 5^n` Trả lời
` 3x^n ( 6x^(n-3) +1) – 2x^n ( 9x^(n-3) -1)` ` = 3x^n . 6x^(n-3) + 3x^n – 2x^n . 9x^(n-3) + 2x^n` ` = 18x^(n+n-3) – 18x^(n+n-3)+ 3x^n + 2x^n` ` = 18x^(2n-3) – 18x^(2n-3) + 5x^n` ` = 5x^n` Trả lời
`3x^n(6x^(n – 3) + 1) – 2x^n(9x^(n – 3) – 1)`
`= 3x^n. 6x^(n – 3) + 3x^n – 2x^n. 9x^(n – 3) + 2x^n`
`= (3. 6). (x^n. x^(n – 3)) – (2. 9). (x^n. x^(n – 3)) + (3x^n + 2x^n)`
`= 18. x^(n + n – 3) – 18. x^(n + n – 3) + 5^n`
`= 18x^(2n – 3) – 18x^(2n – 3) + 5^n`
`= 5^n`
` 3x^n ( 6x^(n-3) +1) – 2x^n ( 9x^(n-3) -1)`
` = 3x^n . 6x^(n-3) + 3x^n – 2x^n . 9x^(n-3) + 2x^n`
` = 18x^(n+n-3) – 18x^(n+n-3)+ 3x^n + 2x^n`
` = 18x^(2n-3) – 18x^(2n-3) + 5x^n`
` = 5x^n`