1)A (x)=x-5

2)B (x)=2x-7+5x

3)C(x)= (2x-7)-(5+x

4)D (x)=2+x-3×(x+1)

5)E(x)=(x-5)×(2x-6)

6)F (x)=(2x-1)×(x×x+9)

7)G (x)= 3×(x+2)+x (x+2)

8)H (x)= 3x×x+5x

9)K (x)=3x×x-7x+4

10)M (x)=x×x-x-2

Đáp án `+` Giải thích các bước giải:

`1,`

Cho đa thức `A(x)=0`

`x-5=0`

`->x=0+5`

`->x=5`

`2,`

Cho đa thức `B(x)=0`

`2 . x-7+5 . x=0`

`->(2 . x+5 . x)-7=0`

`->7 . x-7=0`

`->7 . (x-1)=0`

`->x-1=0:7`

`->x-1=0/7`

`->x-1=0`

`->x=1`

`3,`

Cho đa thức `C(x)=0`

`(2 . x-7)-(5+x)=0`

`->2 . x-7-5-x=0`

`->(2 . x-x)+[(-7)-5]=0`

`->x+(-12)=0`

`->x-12=0`

`->x=0+12`

`->x=12`

`4,`

Cho đa thức `D(x)=0`

`2+x-3 . (x+1)=0`

`->2+x-3 . x-3 . 1=0`

`->2+x-x-3=0`

`->(x-3 . x)+(2-3)=0`

`->(-2 . x)+(-1)=0`

`->(-2 . x)-1=0`

`->-2 . x=0+1`

`->-2 . x=1`

`->x=1:(-2)`

`->x=1/(-2)`

`->x=(-1)/2`

`5,`

Cho đa thức `E(x)=0`

`(x-5) . (2 . x-6)=0`

`->x-5=0, 2 . x-6=0`

`->x=0+5, 2 . x=0+6`

`->x=5, 2 . x=6`

`->x=5, x=6:2`

`->x=5, x=6/2`

`->x=5, x=3`

`6,`

Cho đa thức `F(x)=0`

`(2 . x-1) . (x . x+9)=0`

`->(2 . x-1) . (x^1 . x^1+9)=0`

`->(2 . x-1) . (x^(1+1)+9)=0`

`->(2 . x-1) . (x^2+9)=0`

`->2 . x-1=0, x^2+9=0`

`->2 . x=0+1, x^2=0-9`

`->2 . x=1, x^2=-9`(Loại)

`->x=1:2`

`->x=1/2`

`7,`

Cho đa thức `G(x)=0`

`3 . (x+2)+x . (x+2)=0`

`->(x+2) . (3+x)=0`

`->x+2=0, 3+x=0`

`->x=0-2, x=0-3`

`->x=-2, x=-3`

`8,`

Cho đa thức `H(x)=0`

`3 . x.x +5 . x=0`

`->3 . x^1 . x^1+5 . x=0`

`->3 . x^(1+1)+5 . x=0`

`->3 . x^2+5 . x=0`

`->x . (3 . x+5)=0`

`->x=0, 3 . x+5=0`

`->x=0, 3 . x=0-5`

`->x=0, 3 . x=-5`

`->x=0, x=(-5):3`

`->x=0, x=(-5)/3`

`9,`

Cho đa thức `K(x)=0`

`3 . x . x -7 . x+4=0`

`->3 . x^1 . x^1-7 . x+4=0`

`->3 . x^(1+1)-7 . x+4=0`

`->3 . x^2-7 . x+4=0`

`->3 . x . x-4 . x-3 . x+4=0`

`->(3 . x . x-4 . x) - (3 . x-4)=0`

`->x . (3 . x-4) - 1 . (3 . x-4)=0`

`->(3 . x-4) . (x-1)=0`

`->3 . x-4=0, x-1=0`

`->3 . x=0+4, x=0+1`

`->3 . x=4, x=1`

`->x=4:3, x=1`

`->x=4/3, x=1`

`10,`

Cho đa thức `M(x)=0`

`x . x-x-2=0`

`->x^1 . x^1-x-2=0`

`->x^(1+1)-x-2=0`

`->x^2-x-2=0`

`->x^2+x-2 . x-2=0`

`->(x^2+x)-(2 . x+2)=0`

`->(x . x+x)-(2 . x+2)=0`

`->x . (x+1)-2 . (x+1)=0`

`->(x+1) . (x-2)=0`

`->x+1=0, x-2=0`

`->x=0-1, x=0+2`

`->x=-1, x=2.`