Question

giải giúp em bài 4 ạ

Answer 1

`1)x(1-x)+(x-1)^2`

`=x-x^2+x^2-2x+1`

`=-x+1`

`2)(x-3)^2-x^2+10x-7`

`=x^2-6x+9-x^2+10x-7`

`=4x+2`

`3)(x+2)^2-(x-3)(x+1)`

`=x^2+4x+4-x^2+3x-x+3`

`=6x+7`

`4)(x+4)(x+2)-(x-3)^2`

`=x^2+4x+2x+8-x^2+6x-9`

`=12x-1` 

Answer 2

`(x-3)^2 - x^2 + 10x -7`

`= x^2 - 6x+9-x^2 +10x-7`

`= 4x +2`

`(x+4)(x-2) -(x-3)^2`

`= x^2 + 4x -2x - 8 - (x^2 - 6x+9)`

`= x^2 + 2x - 8 - x^2 + 6x - 9`

`= 8x - 17`

`(x+3)(x-3) - x(23+x)`

`= x^2 - 9 - 23x - x^2`

`= -23x - 9`

`(x-2)(x+2) -(x-3)(x+1)`

`= x^2 - 2^2 - (x^2 - 3x + x - 3)`

`= x^2 - 4 - x^2 + 2x + 3`

`= 2x - 1`

Answer 3

`5) (x-2)^2 + (x-1)(x+5)`

`= x^2 - 4x + 4 + x^2 + 4x -5`

`= 2x^2 -1`

`6) (1-2x)(5-3x)+(4-x)^2`

`= 5-13x+6x^2 +16-8x+x^2`

`=7x^2 - 21x+21`

Answer 4

Bài 4:

1) \(x\left(1-x\right)+\left(x-1\right)^2=x-x^2+x^2-2x+1=1-x\)

2) \(\left(x-3\right)^2-x^2+10x-7=x^2-6x+9-x^2+10x-7=4x+2\)

3) 

\(\left(x+2\right)^2-\left(x-3\right)\left(x+1\right)\\ =x^2+4x+4-\left(x^2+x-3x-3\right)\\ =x^2+4x+4-x^2-x+3x+3\\ =6x+7\)

4) \(\left(x+4\right)\left(x-2\right)-\left(x-3\right)^2\)

\(=x^2-2x+4x-8-\left(x^2-6x+9\right)\\ =x^2+2x-8-x^2+6x-9\\ =8x-17\)

5) \(\left(x-2\right)^2+\left(x-1\right)\left(x+5\right)\)

\(=x^2-4x+4+x^2+5x-x-5=2x^2-1\)

6) \(\left(x+3\right)\left(x-3\right)-x\left(23+x\right)\)

\(=x^2-9-23x-x^2=-23x-9\)

7) \(\left(1-2x\right)\left(5-3x\right)+\left(4-x\right)^2\)

\(=5-3x-10x+6x^2+16-8x+x^2\\ =7x^2-21x+21\)

8) \(\left(x-2\right)\left(x+2\right)-\left(x-3\right)\left(x+1\right)\)

\(=x^2-4-\left(x^2+x-3x-3\right)\\ =x^2-4-x^2-x+3x+3\\ =2x-1\)