a) 12

b) 19

c) 15

d) 30

a, \(\left|x+3\right|=15\)

TH1 : \(x+3=15\Leftrightarrow x=12\)

TH2 : \(x+3=-15\Leftrightarrow x=-18\)

b, \(\left|x-7\right|+13=15\Leftrightarrow\left|x-7\right|=2\)

TH1 : \(x-7=2\Leftrightarrow x=9\)

TH2 : \(x-7=-2\Leftrightarrow x=5\)

c, \(\left|x-3\right|-16=-4\Leftrightarrow\left|x-3\right|=12\)

TH1 : \(x-3=12\Leftrightarrow x=15\)

TH2 : \(x-3=-12\Leftrightarrow x=-9\)

d, \(26-\left|x+9\right|=-13\Leftrightarrow\left|x+9\right|=39\)

TH1 : \(x+9=39\Leftrightarrow x=30\)

TH2 : \(x+9=-39\Leftrightarrow x=-48\)

a) \(\dfrac{7}{9}\times\dfrac{13}{25}\times\dfrac{9}{7}=\left(\dfrac{7}{9}\times\dfrac{9}{7}\right)\times\dfrac{13}{25}=1\times\dfrac{13}{25}=\dfrac{13}{25}\)

b) \(\dfrac{5}{9}\times\dfrac{21}{25}+\dfrac{21}{25}\times\dfrac{4}{9}\)

\(=\dfrac{21}{25}\times\left(\dfrac{5}{9}+\dfrac{4}{9}\right)\)

\(=\dfrac{21}{25}\times1=\dfrac{21}{25}\)

c) \(\dfrac{19}{5}\times\dfrac{11}{16}-\dfrac{9}{5}\times\dfrac{11}{16}\)

\(=\dfrac{11}{16}\times\left(\dfrac{19}{5}-\dfrac{9}{5}\right)\)

\(=\dfrac{11}{16}\times2=\dfrac{22}{16}=\dfrac{11}{8}\)

đề 2 chưa rõ nên mình là 1 đề thôi

|x-7|+13=25

|x-7|= 25-13

|x-7| = 12

\(\orbr{\begin{cases}x-7=-12\\x-7=12\end{cases}}\Rightarrow\orbr{\begin{cases}x=-5\\x=19\end{cases}}\)

Vậy x=-5 hoặc x=19

cậu ơi để |x-3|-16=-4 mình quên chưa viết kết quả cầu làm nốt hộ mình nha

|x-3|-16 = -4

|x-3| = (-4)+16

|x-3| = 12

\(\orbr{\begin{cases}x-3=12\\x-3=-12\end{cases}}\Rightarrow\orbr{\begin{cases}x=15\\x=-9\end{cases}}\)

Vậy x=-9 hoặc x=15

Bài 1: 

a: =83363

a. 86 x 121 - 86 x 22 + 86

= 86 x ( 121 - 22 + 1 )

= 86 x 100

= 8600

b. 25 x 191 - 100 + 25 x 13

= 25 x 191 - 25 x 4 + 25 x 13

= 25 x ( 191 - 4 + 13 )

= 25 x 200

= 5000

Tính giá trị biểu thức:

a. 794 x 105 - 105 : 15

b. 7102 - (1131 - 56) x 4

Tìm x:

a. 86 x 121 - 86 x 22 + 86

= 86 x ( 121 - 22 + 1 )

= 86 x 100

= 8600

b. 25 x 191 - 100 + 25 x 13

= 25 x 191 - 25 x 4 + 25 x 13

= 25 x ( 191 - 4 + 13 )

= 25 x 200

= 5000

Tính nhanh

a. 86 x 121 - 86 x 22 + 86

b. 25 x 191 - 100 + 25 x 13

\(\dfrac{7}{16}+\dfrac{-1}{8}+\dfrac{9}{32}=\dfrac{14}{32}-\dfrac{4}{32}+\dfrac{9}{32}=\dfrac{19}{32}\)

\(\dfrac{5}{4}-\dfrac{25}{30}\times\dfrac{37}{44}+\dfrac{-25}{30}\times\dfrac{13}{44}+\dfrac{-25}{30}\times\dfrac{-6}{44}\)

\(=-\dfrac{25}{30}\times\left(\dfrac{5}{4}+\dfrac{37}{44}+\dfrac{13}{44}-\dfrac{6}{44}\right)\)

\(=-\dfrac{25}{30}\times\left(\dfrac{55}{44}+\dfrac{37}{44}+\dfrac{13}{44}-\dfrac{6}{44}\right)\)

\(=-\dfrac{25}{30}\times\dfrac{99}{44}\)

\(=-\dfrac{5}{6}\times\dfrac{9}{4}\)

\(=-\dfrac{15}{8}\)

\(\left(\dfrac{7}{16}+\dfrac{-1}{8}+\dfrac{9}{32}\right):\dfrac{5}{4}\)

\(=\left(\dfrac{14}{32}+\dfrac{-4}{32}+\dfrac{9}{32}\right):\dfrac{5}{4}\)

\(=\dfrac{19}{32}:\dfrac{5}{4}\)

\(=\dfrac{19}{32}.\dfrac{4}{5}=\dfrac{19.4}{32.5}=\dfrac{19}{40}\)

\(\dfrac{-25}{30}.\dfrac{37}{44}+\dfrac{-25}{30}.\dfrac{13}{44}+\dfrac{-25}{30}.\dfrac{-6}{44}\)

\(=\dfrac{-25}{30}.\left(\dfrac{37}{44}+\dfrac{13}{44}+\dfrac{-6}{44}\right)\)

\(=\dfrac{-25}{30}.\dfrac{44}{44}=\dfrac{-5}{6}.1=-\dfrac{5}{6}\)

a) \(\left|x+3\right|=15\)

\(\Rightarrow\orbr{\begin{cases}x=15-3\\x=-15-3\end{cases}\Rightarrow}\orbr{\begin{cases}x=12\\x=-18\end{cases}}\)

b) Đề sai

c) Đề sai

d) \(26-\left|x+9\right|=-13\)

\(\Rightarrow\left|x+9\right|=26-\left(-13\right)\)

\(\Rightarrow\left|x+9\right|=39\)

\(\Rightarrow\orbr{\begin{cases}x=39-9\\x=-39-9\end{cases}\Rightarrow\orbr{\begin{cases}x=30\\x=-48\end{cases}}}\)

Em ơi ở câu b,c ko có x thì sao mà làm

c,

,\(/x-3/-16=-4\\ =>/x-3/=12\\ =>\hept{\begin{cases}x-3=12\\x-3=-12\end{cases}}=>\hept{\begin{cases}x=15\\x=-9\end{cases}}\)

b,

\(/x-7/+13=25\\ =>/x-7/=12\\ =>\hept{\begin{cases}x-7=12\\x-7=-12\end{cases}}=>\hept{\begin{cases}x=19\\x=-5\end{cases}}\)

Ko pk sai đề đâu ~.~