2x (x-4)^2-(x+5)(x-2)(x+2)+2 (x+5)^2-(x-1)^2 03/07/2021 Bởi Athena 2x (x-4)^2-(x+5)(x-2)(x+2)+2 (x+5)^2-(x-1)^2
`2x . (x-4)^2 – (x+5).(x-2).(x+2) + 2(x+5)^2 – (x-1)^2` `= 2x . (x^2 – 2 . x . 4 + 4^2) – (x+5).(x^2 – 2^2) + 2 . (x^2 + 2 . x . 5 + 5^2) – (x^2 – 2 . x . 1 + 1^2)` ` = 2x . (x^2 – 8x + 16) – (x+5).(x^2 – 4) + 2 . (x^2 + 10x + 25) – (x^2 – 2x+1)` ` = (2x^3 – 16x^2 + 32x) – (x^3 – 4x + 5x^2 – 20) + (2x^2 + 20x + 50) – (x^2 – 2x+1)` ` = 2x^3 – 16x^2 + 32x – x^3 + 4x – 5x^2 + 20 + 2x^2 + 20x + 50 – x^2 + 2x – 1` ` = (2x^3 – x^3) + (-16x^2 – 5x^2 + 2x^2 – x^2) + (32x + 4x + 20x + 2x) + (20+50-1)` ` = x^3 – 20x^2 + 58x + 69` Bình luận
Đáp án: `x^3-20x^2+58x+69.` Giải thích các bước giải: `2x (x-4)^2-(x+5)(x-2)(x+2)+2 (x+5)^2-(x-1)^2` `=2x(x^2-8x+16)-(x+5)(x^2-4)+2(x^2+10x+25)-(x^2-2x+1)` `=2x^3-16x^2+32x-(x^3-4x+5x^2-20)+2x^2+20x+50-x^2+2x-1` `=2x^3-16x^2+32x-x^3+4x-5x^2+20+2x^2+20x+50-x^2+2x-1` `=(2x^3-x^3)+(-16x^2-5x^2+2x^2-x^2)+(32x+4x+20x+2x)+(20+50-1)` `=x^3-20x^2+58x+69.` Bình luận
`2x . (x-4)^2 – (x+5).(x-2).(x+2) + 2(x+5)^2 – (x-1)^2`
`= 2x . (x^2 – 2 . x . 4 + 4^2) – (x+5).(x^2 – 2^2) + 2 . (x^2 + 2 . x . 5 + 5^2) – (x^2 – 2 . x . 1 + 1^2)`
` = 2x . (x^2 – 8x + 16) – (x+5).(x^2 – 4) + 2 . (x^2 + 10x + 25) – (x^2 – 2x+1)`
` = (2x^3 – 16x^2 + 32x) – (x^3 – 4x + 5x^2 – 20) + (2x^2 + 20x + 50) – (x^2 – 2x+1)`
` = 2x^3 – 16x^2 + 32x – x^3 + 4x – 5x^2 + 20 + 2x^2 + 20x + 50 – x^2 + 2x – 1`
` = (2x^3 – x^3) + (-16x^2 – 5x^2 + 2x^2 – x^2) + (32x + 4x + 20x + 2x) + (20+50-1)`
` = x^3 – 20x^2 + 58x + 69`
Đáp án:
`x^3-20x^2+58x+69.`
Giải thích các bước giải:
`2x (x-4)^2-(x+5)(x-2)(x+2)+2 (x+5)^2-(x-1)^2`
`=2x(x^2-8x+16)-(x+5)(x^2-4)+2(x^2+10x+25)-(x^2-2x+1)`
`=2x^3-16x^2+32x-(x^3-4x+5x^2-20)+2x^2+20x+50-x^2+2x-1`
`=2x^3-16x^2+32x-x^3+4x-5x^2+20+2x^2+20x+50-x^2+2x-1`
`=(2x^3-x^3)+(-16x^2-5x^2+2x^2-x^2)+(32x+4x+20x+2x)+(20+50-1)`
`=x^3-20x^2+58x+69.`