rút gọn 4x^2+4x+1-(2x-1)^2 và (x+5).(x^2+5x+25)-10x.(x+5)-x^3 06/07/2021 Bởi Athena rút gọn 4x^2+4x+1-(2x-1)^2 và (x+5).(x^2+5x+25)-10x.(x+5)-x^3
`4x^2 + 4x + 1 – (2x-1)^2` ` = 4x^2 + 4x + 1 – (4x^2 – 4x + 1)` ` = 4x^2 + 4x + 1 – 4x^2 + 4x – 1` ` = 8x` `(x+5)(x^2+ 5x + 25) – 10x.(x+5) – x^3` `= (x+5).(x^2 + 5x + 25 – 10x) – x^3` ` = (x+5).(x^2 – 5x + 25) – x^3` ` = x^3 + 5^3 -x^3` ` = 5^3` ` = 125` Bình luận
`4x^2 + 4x + 1 – (2x-1)^2`
` = 4x^2 + 4x + 1 – (4x^2 – 4x + 1)`
` = 4x^2 + 4x + 1 – 4x^2 + 4x – 1`
` = 8x`
`(x+5)(x^2+ 5x + 25) – 10x.(x+5) – x^3`
`= (x+5).(x^2 + 5x + 25 – 10x) – x^3`
` = (x+5).(x^2 – 5x + 25) – x^3`
` = x^3 + 5^3 -x^3`
` = 5^3`
` = 125`