Bài 4:

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

\(5\left(x-y\right)-y\left(x-y\right)=\left(x-y\right)\left(5-y\right)\)

\(x^2-12x+36=\left(x-6\right)^2\)

Phân tích đa thức thành nhân tử:

\(6xy+5x-5y-3x^2-3y^2\)

\(=-3x^2+6xy-3y^2+5x-5y\)

\(=-3\left(x^2-2xy+y^2\right)+5\left(x-y\right)\)

\(=-3\left(x-y\right)^2+5\left(x-y\right)\)

\(=\left(x-y\right)\left[-3\left(x-y\right)+5\right]\)

\(=\left(x-y\right)\left(-3x+3y+5\right)\)

Thực hiện phép tính:

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

\(=\left[x^2+\left(x-3\right)\right]\left[x^2-\left(x-3\right)\right]\)

\(=\left(x^2\right)^2-\left(x-3\right)^2\)

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

\(=x^4-x^2+6x-9\)

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

\(=\left(5x^2+15x-x-3\right)-\left(5x^2-4x-10x+8\right)\)

\(=5x^2+15x-x-3-5x^2+4x+10x-8\)

\(=28x-11\)

Tính nhanh:

a)\\(2004^2-16\\)

\\(=2004^2-4^2\\)

\\(=\\left(2004-4\\right)\\left(2004+4\\right)\\)

\\(=2000.2008\\)

\\(=40160000\\)

b)\\(892^2+892.216+108^2\\)

\\(=892^2+2.892.108+108^2\\)

\\(=\\left(892+108\\right)^2\\)

\\(=1000^2\\)

\\(=1000000\\)

c)\\(10,2.9,8-9,8.0,2+10,2^2-10,2.0,2\\)

\\(=9,8\\left(10,2-0,2\\right)+10,2\\left(10,2-0,2\\right)\\)

\\(=9,8.10+10,2.10\\)

\\(=10\\left(9,8+10,2\\right)\\)

\\(=10.20\\)

\\(=200\\)

Bài 2: 

a: =>x-35=-23

=>x=12

b: =>|x-8|=13

=>x-8=13 hoặc x-8=-13

=>x=21 hoặc x=-5

Bài 1: 

a: =42-98-42+12-12=-98

b: =10x4x3x(-25)=40x(-25)x3=-1000x3=-3000

a,=0,9:(4/5.1,25+1:1/3)
=0,9:(1+3)

=0,9:4

=0,225

b,=9,6:6-0,6

=1,6-0,6

=1

c,=7/2.11/4-7/2.5/4

=7/2.(11/4-5/4)

=7/2.3/2

=21/4

a) \(\frac{3x+5}{2\left(x-1\right)}+\frac{4}{x-2}=\frac{\left(3x+5\right)\left(x-2\right)+4\cdot2\left(x-1\right)}{2\left(x-1\right)\left(x-2\right)}=\frac{3x^2-6x+5x-10+8x-8}{2\left(x-1\right)\left(x-2\right)}\)

\(=\frac{3x^2+7x-18}{2\left(x-1\right)\left(x-2\right)}\)

b) \(\frac{2x^2+1}{4x^2-2x}+\frac{3-3x}{1-2x}+\frac{3}{2x}=\frac{2x^2+1+4x\left(3-3x\right)+2\cdot3\left(1-2x\right)}{4x\left(1-2x\right)}=\frac{2x^2+1+12-12x+6-12x}{4x\left(1-2x\right)}\)\(=\frac{2x^2-24x+19}{4x\left(1-2x\right)}\)

Đề này... bạn xem lại đi. Chứ thế này thì dùng máy tính cũng không làm nổi T-T

a) \(22\frac{1}{2}\cdot\frac{7}{9}+50\%-1,25\)

\(=\frac{45}{2}\cdot\frac{7}{9}+\frac{50}{100}-\frac{125}{100}\)

\(=\frac{5}{2}\cdot\frac{7}{1}+\frac{1}{2}-\frac{5}{4}\)

\(=\frac{35}{2}+\frac{1}{2}-\frac{5}{4}=18-\frac{5}{4}=\frac{67}{4}\)

b) \(1,4\cdot\frac{15}{49}-\left(\frac{4}{5}+\frac{2}{3}\right):2\frac{1}{5}\)

\(=\frac{7}{5}\cdot\frac{15}{49}-\frac{22}{15}:\frac{11}{15}\)

\(=\frac{1}{1}\cdot\frac{3}{7}-\frac{22}{15}\cdot\frac{15}{11}\)

\(=\frac{3}{7}-2=\frac{3-14}{7}=\frac{-11}{7}\)

c) \(\left(-\frac{1}{2}\right)^2-\frac{7}{16}:\frac{7}{4}+75\%\)

\(=\frac{1}{4}-\frac{7}{16}\cdot\frac{4}{7}+\frac{75}{100}\)

\(=\frac{1}{4}-\frac{1}{4}+\frac{3}{4}=\frac{3}{4}\)

Bài 2  Bạn tự làm nhé

1.a,\(22\frac{1}{2}.\frac{7}{9}+50\%-1,25\)

\(=\frac{45}{2}.\frac{7}{9}+\frac{1}{2}-\frac{5}{4}\)

\(=\frac{35}{2}+\frac{1}{2}-\frac{5}{4}\)

\(=\frac{67}{4}\)

b,Các phép tính khác làm tương tự

Đổi các số ra hết thành phân số,có ngoặc thì lm ngoặc trc,Xoq đến nhân chia trước dồi mới cộng trừ

c,tương tự

2.

a,\(1\frac{3}{5}+\frac{7}{12}\div x=\frac{-9}{4}\)

\(\frac{8}{5}+\frac{7}{12}\div x=\frac{-9}{4}\)

\(\frac{7}{12}\div x=\frac{-77}{20}\)

Đến đây dễ bạn tự làm

b,\(\left(2\frac{4}{5}.x+50\right)\div\frac{2}{3}=-51\)

\(\left(\frac{14}{5}x+50\right)\div\frac{2}{3}=-51\)

\(\frac{14}{5}x+50=-34\)

\(\frac{14}{5}x=-84\)

Tự làm tiếp

c,\(\left|\frac{3}{4}.x-\frac{1}{2}\right|=\frac{1}{4}\)\(\Rightarrow\left|\frac{3}{4}x-\frac{1}{2}\right|=\varnothing\)