Bài 1:

a) \(6,25.0,75.32\)

\(=6,25.0,75.8.4\)

\(=\left(6,25.8\right).\left(0,75.4\right)\)

\(=50.3=150\)

b)\(16,75.3,14.\left(45,5-2.22,75\right)\)

=\(16,75.3,14.\left(45,5-45,5\right)\)

\(=16,75.3,14.0\)

\(=0\)

Bài 2:

a)\(\dfrac{3}{2}.\dfrac{4}{5}-x=\dfrac{2}{3}\)

\(\dfrac{6}{5}-x=\dfrac{2}{3}\)

\(\Rightarrow x=\dfrac{6}{5}-\dfrac{2}{3}=\dfrac{8}{15}\)

b)\(\left[3.\left(x+2\right):7\right].4=120\)

\(\left[3.\left(x+2\right):7\right]=120:4=30\)

\(\Rightarrow3\left(x+2\right)=30.7=210\)

\(\Rightarrow x+2=210:3=70\)

\(\Rightarrow x=68\)

Gọi số cần thêm vào cả tử và mẫu là x(\(x\in N\)*)

Theo bài ra ta có:

\(\dfrac{11+x}{16+x}=\dfrac{4}{5}\)

\(\Rightarrow4\left(16+x\right)=5\left(11+x\right)\)

\(\Rightarrow64+4x=55+5x\)

\(\Rightarrow5x-4x=64-55\Rightarrow x=9\)

Vậy.............

16,75 x 3,14 x ( 45,5 - 2 x 22,75)

=16,75 x 3,14 x ( 45,5 - 45,5)

=16,75 x 3,14 x 0

=0

( 4,5 x 16 - 1,7 ) : ( 4,5 x 15 + 2,8)

=( 4,5 x 15 + 4,5 - 1,7 ) : ( 4,5 x 15 + 2,8)

=( 4,5 x 15 + 2,8 ) : ( 4,5 x 15 + 2,8)

=1

Bài 1

2/5 - 3/5 : (0,75 + 30%)

= 2/5 - 3/5 : 21/20

= 2/5 - 4/7

= -6/35

‐--------------------

Bài 2

a) x/6 = -11/3

x = -11/3 . 6

x = -22

b) 16/5 của x là 48

x = 48 : 16/5

x = 15

bài1

2/5-3/5:(0,75+30%)=2/5-3/5:(75/100+30/100)

                               =2/5-3/5:105/100

                               =2/5-3/5:21/20

                               = 2/5-3/5. 20/21

                               =2/5-1/1.4/7

                               =2/5-4/7

                               =2/5+-4/7

                               =14/35+-20/35

                               =34/35

Giai nhanh giup mik với ạ mik cần gấp.Làm hết ạ

\(1,\\ a,=\dfrac{7}{19}\times\left(\dfrac{1}{3}+\dfrac{2}{3}\right)=\dfrac{7}{19}\times1=\dfrac{7}{19}\\ b,=\dfrac{2}{5}+\left(\dfrac{3}{4}+\dfrac{1}{4}\right)=\dfrac{2}{5}+1=\dfrac{7}{5}\\ 2,\\ a,=15\times\left(\dfrac{2121}{4343}+\dfrac{222222}{434343}\right)\\ =15\times\left(\dfrac{2121:101}{4343:101}+\dfrac{222222:10101}{434343:10101}\right)\\ =15\times\left(\dfrac{21}{43}+\dfrac{22}{43}\right)=15\times\dfrac{43}{43}=15\times1=15\)

\(3,\)

Cạnh \(AC=\) chu vi ABC \(-AB-BC=\dfrac{4}{5}-\dfrac{1}{5}-\dfrac{1}{4}=\dfrac{3}{5}-\dfrac{1}{4}=\dfrac{7}{20}\left(m\right)\) 

Vì \(\dfrac{7}{20}>\dfrac{5}{20}>\dfrac{4}{20}\Rightarrow\dfrac{7}{20}>\dfrac{1}{4}>\dfrac{1}{5}\) nên \(AC>BC>AB\)

1) 2,75 - 5/6 × 2/5 = 2,75 - (5/6) × (2/5) = 2,75 - 1/3 = 2,75 - 0,33 = 2,42

2) 1,25 - (5/6 - 0,75) - 3/5 = 1,25 - (5/6 - 0,75) - 3/5 = 1,25 - (5/6 - 3/4) - 3/5 = 1,25 - (5/6 - 9/12) - 3/5 = 1,25 - (10/12 - 9/12) - 3/5 = 1,25 - 1/12 - 3/5 = 1,25 - 0,08 - 0,6 = 1,25 - 0,68 = 0,57

3) 4/9 × 0,75 + 8/5 + 3,125 = (4/9) × 0,75 + 8/5 + 3,125 = 0,44 + 8/5 + 3,125 = 0,44 + 1,6 + 3,125 = 0,44 + 4,725 = 5,165

4) 1,125 - 4/7 - 0,12 = 1,125 - (4/7) - 0,12 = 1,125 - 0,57 - 0,12 = 0,435 - 0,12 = 0,315

5) (1/3 + 0,4) × 3,5 + (1/6 + 0,75) × 6/5

bài 1 . 10

bài 2 . 12

bài 3 . 6

bài 4 .  20/14

bài 5 . 5/20

mình chỉ làm được vậy thôi

\(\text{Bài 4:}\)

\(a.\left|x-\frac{3}{5}\right|< \frac{1}{3}\Rightarrow\orbr{\begin{cases}x-\frac{3}{5}< \frac{1}{3}\\x-\frac{3}{5}>-\frac{1}{3}\end{cases}}\)\(\Rightarrow\orbr{\begin{cases}x< \frac{14}{15}\\x>\frac{4}{15}\end{cases}\Rightarrow\frac{4}{15}< x< \frac{14}{15}}\)

\(b.\left|-5,5\right|=5,5\)

\(\Rightarrow\left|x+\frac{11}{2}\right|>5,5\Rightarrow\orbr{\begin{cases}x+\frac{11}{2}>5,5\\x+\frac{11}{2}< -5,5\end{cases}}\)\(\Rightarrow\orbr{\begin{cases}x>0\\x< -11\end{cases}}\)