\(\frac{a}{b}=\frac{c}{d}\)

=> \(\frac{a}{c}=\frac{b}{d}=>\frac{a^2}{c^2}=\frac{c^2}{d^2}=\frac{a.b}{b.c}=\frac{a}{c}\)

=> \(\frac{a^2+b^2}{b^2+c^2}=\frac{a}{c}\)

=> dpcm

a) 327+48+73+12

= ( 327 + 73 ) + ( 48 + 12 )

= 300 + 100

= 400

b) 4.5.25.24

=  ( 4.25).(5.24)

= 100 . 120

= 12000

c) 30.19+30.81

= 30.(19 + 81 )

= 30.100

= 3000

d) 27.48+27.50+54

=27.48 + 27.50 + 27.2

= 27.(48 + 50 + 2)

= 27.100

= 2700

e) 36.67+18.66

= 36.67 + 18.2.33

= 36.67 + 36.33

= 36.(67 + 33)

= 36.100

= 3600

Chúc bạn học tốt! (^ _ ^)

Đây là toán lớp 3 thì có lớp 6 j mà đễ như thế này

a) 327 + 48 + 73 + 12

   = ( 327 + 73 ) + ( 48 + 12 )

   = 400 + 60

   = 460

Đáp án C không phải là tác dụng của dấu gạch ngang

C Đánh dâu cun từ với ý nghĩa đặc biệt.

10. In America, soccer is the usual word for…………..       

A. volleyball               B. football                               C. basketball                                    D. baseball

11.…………..does the plane fly? It flies at 500 miles an hour.

A. How much             B. How fast                             C. How                                    D. How long

12. Hoa’s brother is a…………..He repairs cars in a garage.

A. writer                      B. mechanic                            C. journalist                                    D. farmer

13. He looks so…………... His face turns red when he talks with strangers.

            A. friendly                   B. creative                              C. clever                                    D. shy

14. How many…………..  are there in your house?

A. kitchen                   B. room                       C. rooms         D. living room

15. He wears thick…………... They make him so intelligent.

A. shoulders                B. tails                                     C. glasses                                    D. necks

16. She has…………..books than Linh.                    

A. much                      B. more                                   C. most                                    D. many

17. She’s very beautiful. She has long black…………..and brown…………..       

A. face/fingers             B. hair/ eyes                            C. nose/foots                                    D. arm/ears

18. Let’s…………..to Huong’s house.                      

A. come                      B. to come                              C. comes                                    D. coming

19. What…………..great idea!                     

A. a                             B. Ø                                         C. the                                 D. an

a)   ( 2x + 3)^2 = 121

        2x + 3^2   = 121

         2x + 9      = 121

                 2x    = 121 - 9

                  2x   =   112

                     x  =  112 : 2

                      x = 56

Mấy câu sau tự làm nhé bạn 

a) (2x + 3)² = 121

    (2x + 3)² = 11²

^=>   2x + 3 = 11

     2x       = 11 - 3

     2x       = 8

       x      = 8 : 2

       x       = 4

b) (75 - 3x)³ = 27

    ( 75 - 3x)³ = 3³

=> 75 - 3x     = 3

            3x     = 75- 3

            3x     =  72

              x     = 72 : 3

              x      = 24

a,11²=121

=>(2x+3)=11

=>2x=8=>x=4

b,3³=27

=>75-3x=3

=>3x=72

=>x=24

c,16¹³=(2⁴)¹³

=2^4.13=2⁵²

=>2^x=2⁶⁰:2⁵²

=>2^x=2⁸=>x=8

CHUC BN HOC TOT

Đặt a/b=c/d=k

=>a=bk; c=dk

\(\dfrac{a+2b}{a}=\dfrac{bk+2b}{bk}=\dfrac{k+2}{k}\)

\(\dfrac{c+2d}{c}=\dfrac{dk+2d}{dk}=\dfrac{k+2}{k}\)

=>\(\dfrac{a+2b}{a}=\dfrac{c+2d}{c}\)

Ta có a+2/b+2 = a/b+2 + 2/b+2 = a(b+2)/b+2 + 2(b+2)/b+2 = a+2

Do a+2 > a/b =>  a+2/b+2 >a/b

mik làm đại ko bik đúng hay sai đâu nha

Xét tích : \(a\left(b+2\right)=ab+2a\)

               \(b\left(a+2\right)=ab+2b\)

Nếu \(a>b\)thì \(ab+2a>ab+2b\)

                     hay \(a\left(b+2\right)>b\left(a+2\right)\)

                     \(\Rightarrow\frac{a}{b}>\frac{a+2}{b+2}\)

Nếu \(a< b\)thì \(ab+2a< ab+2b\)

                     hay \(a\left(b+2\right)< b\left(a+2\right)\)

                     \(\Rightarrow\frac{a}{b}< \frac{a+2}{b+2}\)

Nếu \(a=b\)thì \(ab+2a=ab+2b\)

                     hay \(a\left(b+2\right)=b\left(a+2\right)\)

                     \(\Rightarrow\frac{a}{b}=\frac{a+2}{b+2}\)