(x + 1)²

= x² + 2x + 1 

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

= x² + 2x + 1 

Bài 1: 

a: =25+75=100

b: =60-17-43+12=12

c: =-2-18=-20

d: =-3+36-17=36-20=16

Bài 2: 

a: =-102

b: =-1000

c: =12x15=180

d: =21x(-10)=-210

B1

a 100

b 12

c -20

d 16

B2

a -102

b -1000

c 180

d -210

Bài 1:Tính

 a)(-12)+25+75+12 = 100

b)60+12+(-17)+(-43)=12
c)(-2)+(-87)+(-18)+87=-20
d)(-1)+(-2)+36+(-17)=16
Bài 2:Tính
b)8 . (-125)=-100
c)(-12) . (-15)=180
d)21 . (- 3)+(- 21 ) . 7=-210

a) Ta có: \(1+\left(-2\right)+3+\left(-4\right)+...+2021\)

\(=\left(1-2\right)+\left(3-4\right)+...+\left(2019-2020\right)+2021\)

\(=\left(-1\right)+\left(-1\right)+...+\left(-1\right)+2021\)

\(=-1010+2021=1011\)

1+(-2)+3+(-4)+....+2021

=(1+3+5+.....+2021)-(2+4+6+....+2020)

=\(\dfrac{\left(1+2021\right)\cdot2021}{2}-\dfrac{\left(2+2020\right)\cdot2020}{2}=1010\cdot2021-1010\cdot2020\\ =1010\cdot\left(2021-2020\right)=1010\cdot1\\ =1010\)

1 + (-2) + 3 + (-4) +......+ 2021

= ( 1 - 2 ) + ( 3 - 4 ) +....+ ( 2019 - 2020 ) + 2021

= (-1) + (-1) +.....+ (-1) + 2021

Từ 1 đến 2020 có số số hạng là : 

( 2020 - 1 ) : 1 + 1 = 2020 ( số hạng ) 

⇒ 1 + 2021 = 2022

A:2 = 1/6 + 1/12 + 1/20 +...+ 1/380 = 1/(2x3) + 1/(3x4) + 1/(4x5) + ... + 1/(19x20) = 1/2 - 1/3+1/3 - 1/4 +....+ 1/19- 1/20 = 1/2 - 1/20 = 9/20 Suy ra A = 9/20 x 2 = 9/10

10 - 4,86 : 1,8

= 10 - 2,7

= 7,3

= 7,3 nha

1:

a: \(\sqrt{36}-\sqrt{100}=6-10=-4\)

b: Để \(\sqrt{\dfrac{2}{2x-1}}\) có nghĩa thì \(\dfrac{2}{2x-1}>=0\)

=>2x-1>0

=>x>1/2

2:

a: \(A=\dfrac{\left(15\sqrt{180}-5\sqrt{200}-3\sqrt{450}\right)}{\sqrt{10}}\)

\(=15\sqrt{\dfrac{180}{10}}-5\sqrt{\dfrac{200}{10}}-3\sqrt{\dfrac{450}{10}}\)

\(=15\sqrt{18}-5\sqrt{20}-3\sqrt{45}\)

\(=45\sqrt{2}-10\sqrt{5}-9\sqrt{5}\)

\(=45\sqrt{2}-19\sqrt{5}\)

b: \(B=\sqrt{32}-\sqrt{50}-16\sqrt{\dfrac{1}{8}}\)

\(=4\sqrt{2}-5\sqrt{2}-\dfrac{16}{\sqrt{8}}\)

\(=-\sqrt{2}-2\sqrt{8}=-\sqrt{2}-4\sqrt{2}=-5\sqrt{2}\)

a)

\(\left(y+1\right)^2\)

= \(y^2+2y+1\)

b)

\(\left(y-1\right)^2\)

= \(y^2-2y+1\)

a 

=y²+ 2y1 + 1²

=y² + 2y +1

b 

=y² -2y1 + 1²

=y² -2y1 + 1²

\(\left(\dfrac{1}{6}+4\right)\times\dfrac{3}{10}=\left(\dfrac{1}{6}+\dfrac{24}{6}\right)=\dfrac{25}{6}\times\dfrac{3}{10}=\dfrac{5}{4}\)

\(\left(\dfrac{1}{8}-\dfrac{1}{9}\right)\times\dfrac{3}{2}=\left(\dfrac{9}{72}-\dfrac{8}{72}\right)\times\dfrac{3}{2}=\dfrac{1}{72}\times\dfrac{3}{2}=\dfrac{1}{48}\)

a) = 25/6 x 3/10

= 5/4

b) = 1/72 x 3/2 

= 1/48