x + 78 - 54 = 56 x 7

x + 78 - 54 = 392

x + 78        = 392 + 54

x + 78        = 446

x                = 446 - 78

x                = 368

x+78-54=56x7

x+78-54=392

x+78=392+54

x+78=446

x=446-78

x=368

x + 78 -54= 392

x+78       = 392 +54

x+78        =446

x            =446- 78

x                =368

=176 

k nha 

mik kb rùi 

\(78+98=176\)

78+98=176

32 , 65 x 45 

= 1469, 25

Ủng hộ mk nha

146925. tui kết bạn nè .

32.65x45=1469.25

23 × 45 = 1035

23x45=1035

23 × 45 = 1035

\(=\frac{3}{4}\left(\frac{1}{5.9}+\frac{1}{9.13}+...+\frac{1}{41.45}\right)\)

\(=\frac{3}{4}\left(\frac{1}{5}-\frac{1}{9}+\frac{1}{9}-\frac{1}{13}+...+\frac{1}{41}-\frac{1}{45}\right)\)

\(=\frac{3}{4}\left(\frac{1}{5}-\frac{1}{45}\right)\)

\(=\frac{3}{4}\times\frac{8}{45}\)

\(=\frac{2}{15}\)

giải giùm đi

\(A=\frac{3}{5\cdot9}+\frac{3}{9\cdot13}+\frac{3}{13\cdot17}+...+\frac{3}{37\cdot41}+\frac{3}{41\cdot45}\)

\(\frac{4A}{3}=\frac{9-5}{5\cdot9}+\frac{13-9}{9\cdot13}+\frac{17-13}{13\cdot17}+...+\frac{41-37}{37\cdot41}+\frac{45-41}{41\cdot45}\)

\(\frac{4A}{3}=\frac{1}{5}-\frac{1}{9}+\frac{1}{9}-\frac{1}{13}+\frac{1}{13}-\frac{1}{15}+...+\frac{1}{37}-\frac{1}{41}+\frac{1}{45}-\frac{1}{45}\)

\(\frac{4A}{3}=\frac{1}{5}-\frac{1}{45}=\frac{9-1}{45}=\frac{8}{45}\Rightarrow A=\frac{8}{45}\cdot\frac{3}{4}=\frac{2}{15}\)

\(\dfrac{42x45}{5x7}=\dfrac{7x6x5x9}{5x7}=\dfrac{54}{1}=54\)

\(\dfrac{54x56}{7x9}=\dfrac{6x9x7x8}{7x9}=\dfrac{48}{1}=48\)

`(42 xx45)/(5xx7) =( 6xx7xx9xx5)/(5xx7) = 6 xx9 = 54`

`(54xx56)/(7xx9) = (9xx6xx7xx8)/(7xx9) = 6xx8 = 48`

đúng

12 x 9 + 9,7

= 108 + 9,7

= 117,7

chúc bạn hok tốt ^-^

117,7 nha !

   12 x 9 +9,7

= 108 +9,7

= 117,7

\(3A=\frac{6}{3\times\left(3+6\right)}+\frac{15}{9\times\left(9+15\right)}+...+\frac{39}{84\times\left(84+39\right)}\)

\(=\frac{1}{3}-\frac{1}{9}+\frac{1}{9}-\frac{1}{24}+...+\frac{1}{84}-\frac{1}{123}=\frac{1}{3}-\frac{1}{123}=\frac{40}{123}\)

\(\Rightarrow A=\frac{40}{3.123}=\frac{40}{369}\)

mình biết mà tính mệt quá

163/25+63/4

2227/100

tk mk nha bn iu