1

b. 6x(x - 5) - x(6x + 3)

= x(6x - 30) - x(6x + 3)

= x(6x - 30 - 6x - 3)

= x(-33)

= -33x

\(1,\\ a,=-35x^5y^4z\\ b,=6x^2-30x-6x^2-3x=-33x\\ c,=x^3-9x^2-2x^2+18x-x+9=x^3-11x^2+17x+9\\ 2,\\ A\left(x\right)+B\left(x\right)=10-2x+4x^3-5x^2-10x^3-5x+6x^2-20\\ =-6x^3+x^2-7x-10\\ A\left(x\right)-B\left(x\right)=10-2x+4x^3-5x^2+10x^3+5x-6x^2+20\\ =14x^3-11x^2+3x+30\\ 3,\\ a,M\left(x\right)=5x+20=0\\ \Leftrightarrow x=-4\\ b,N\left(x\right)=100x^2-49=0\\ \Leftrightarrow\left(10x-7\right)\left(10x+7\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=\dfrac{7}{10}\\x=-\dfrac{7}{10}\end{matrix}\right.\\ c,P\left(x\right)=3x-15=0\\ \Leftrightarrow x=5\)

Bài 1;

a)\(5x^3yz.\left(-7x^2y^3\right)=-35.x^5y^4z\)

b)\(6x\left(x-5\right)-x\left(6x+3\right)=6x^2-30x-6x^2-3x=-33x\)

c) \(\left(x-9\right)\left(x^2-2x-1\right)=x^3-2x^2-x-9x^2+18x+9=x^3-11x^2+17x+9\)

x+2x+3x+...+100x=5500

5500=((1+100)*50)x

=5050

bạn sai đề

a)<=> 3x-5-x=0

   <=>    2x-5=0

   <=>        x=5/2

c) x.(1+2+3+4+...+100)=0

    x.5050=0

     x=0:5050=0

Vậy x=0

d) x.(1+2+3+4+5+...+100)=5050

    x.5050=5050

    x=1

Vậy x=1

e) x+1+x+2+x+3+x+4+...+x+100=5050

    (x+x+x+x+...+x)+(1+2+3+4+...+100)=5050

     100 số hạng x

    x.100+5050=5050

    x.100=0

    x=0

Vậy x=0

a , x = \(\frac{5}{2}\)

1: A=(x-1)^2>=0

Dấu = xảy ra khi x=1

5: B=-(x^2+6x+10)

=-(x^2+6x+9+1)

=-(x+3)^2-1<=-1

Dấu = xảy ra khi x=-3

2: B=x^2+4x+4-9

=(x+2)^2-9>=-9

Dấu = xảy ra khi x=-2

6: =-(x^2-5x-3)

=-(x^2-5x+25/4-37/4)

=-(x-5/2)^2+37/4<=37/4

Dấu = xảy ra khi x=5/2

3: =x^2+x+1/4-1/4

=(x+1/2)^2-1/4>=-1/4
Dấu = xảy ra khi x=-1/2

7: =4x^2+4x+1-2

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

Dấu = xảy ra khi x=-1/2

a: =>5x-2=0 hoặc 2x+1/3=0

=>x=-1/6 hoặc x=2/5

b: Đặt x/2=y/3=k

=>x=2k; y=3k

xy=54

=>6k^2=54

=>k^2=9

=>k=3 hoặc k=-3

TH1: k=3

=>x=6; y=9

TH2: k=-3

=>x=-6; y=-9

c: =>5050x=-213

=>x=-213/5050