Hình C

hok tốt ~

Trả lời:

Hình C bn nhé

Đây ko phải toán lớp 7 đâu bạn

Mk nghĩ đây toán lớp 4

a5 = 5 vi tat ca phep cchia deu = 1

\(\left|x-y\right|\ge\left|x\right|-\left|y\right|\)

\(\Leftrightarrow\left(x-y\right)^2\ge\left(\left|x\right|-\left|y\right|\right)^2\)

\(\Leftrightarrow x^2-2xy+y^2\ge x^2+y^2-2.\left|x\right|.\left|y\right|\)

\(\Leftrightarrow xy\le\left|x\right|.\left|y\right|\) (luôn đúng)

Ta có đpcm

mình hông hiểu lắm

Câu 37:

a: \(\frac{-7}{15}\cdot\frac{5}{-21}\)

\(=\frac{-7}{-21}\cdot\frac{5}{15}\)

\(=\frac13\cdot\frac13=\frac19\)

b: \(-\frac49:\frac23=-\frac49\cdot\frac32=-\frac{12}{18}=-\frac23\)

c: \(-\frac{3}{15}\cdot\frac{35}{-7}=\frac{3}{15}\cdot\frac{35}{7}=\frac15\cdot5=1\)

d: \(-\frac49:\left(-2\frac23\right)=-\frac49:\frac{-8}{3}=\frac49:\frac83=\frac49\cdot\frac38=\frac{12}{72}=\frac16\)

Câu 36:

a: \(-3,5\cdot\frac{-4}{21}=\frac{-3,5\cdot\left(-4\right)}{21}=\frac{14}{21}=\frac23\)

b: \(1\frac23\cdot\left(-2\frac13\right)=-\frac53\cdot\frac73=-\frac{35}{9}\)

c: \(\left(-2,5\right):\frac{3}{-4}=\left(-2,5\right)\cdot\frac{\left(-4\right)}{3}=\frac{10}{3}\)

d: \(\left(-8\frac25\right):\left(-2\frac45\right)=\frac{-42}{5}:\frac{-14}{5}=\frac{42}{14}=3\)

Câu 35:

a: \(\frac32\cdot\frac{-2}{25}=\frac{3}{25}\cdot\frac{-2}{2}=-\frac{3}{25}\)

b: \(\frac{-8}{5}\cdot\frac{-3}{4}=\frac85\cdot\frac34=\frac{24}{20}=\frac65\)

c: \(-\frac{15}{4}:\frac{-21}{10}=\frac{15}{4}:\frac{21}{10}=\frac{15}{4}\cdot\frac{10}{21}=\frac{10}{4}\cdot\frac{15}{21}=\frac52\cdot\frac57=\frac{25}{14}\)

d: \(-\frac{15}{7}:\frac{5}{14}=-\frac{15}{7}\cdot\frac{14}{5}=\frac{-210}{35}=-6\)

Câu 34:

\(-3\frac15\cdot2,5=-\frac{16}{5}\cdot\frac52=-\frac{16}{2}=-8\)

Câu 33:

a: \(\frac{-1}{21}+\frac{-1}{14}=\frac{-2}{42}+\frac{-3}{42}=\frac{-2-3}{42}=-\frac{5}{42}\)

b: \(\frac{-3}{7}+\frac{-2}{9}=\frac{-27}{63}+\frac{-14}{63}=-\frac{27+14}{63}=-\frac{41}{63}\)

c: \(\frac{-5}{12}+\frac{7}{18}=-\frac{15}{36}+\frac{14}{36}=\frac{-15+14}{36}=\frac{-1}{36}\)

d: \(\frac{-4}{15}+0,75=-\frac{4}{15}+\frac34=-\frac{16}{60}+\frac{45}{60}=\frac{45-16}{60}=\frac{29}{60}\)

e: \(-\frac23+1,1=-\frac23+\frac{11}{10}=-\frac{20}{30}+\frac{33}{30}=\frac{33-20}{30}=\frac{13}{30}\)

f: \(-3\frac12-4\frac14=-\frac72-\frac{17}{4}=\frac{-14}{4}-\frac{17}{4}=-\frac{31}{4}\)

Câu 32:

a: \(\frac{1}{12}+\frac{-3}{12}=\frac{1-3}{12}=-\frac{2}{12}=-\frac16\)

b: \(\frac78-\frac54=\frac78-\frac{10}{8}=\frac{7-10}{8}=-\frac38\)

c: \(1\frac25+3\frac35=1+\frac25+3+\frac35=4+1=5\)

d: \(\frac{-14}{20}+0,6=-\frac{14}{20}+\frac{12}{20}=-\frac{2}{20}=-\frac{1}{10}\)

Câu 31:

\(A=-\frac15+\frac{8}{15}\)

\(=-\frac{3}{15}+\frac{8}{15}=\frac{5}{15}=\frac13\)

Các cặp góc so le trong là: \(\hat{A_1};\hat{B_7}\) ; \(\hat{A_4};\hat{B_6}\)

Các cặp góc đồng vị là: \(\hat{A_2};\hat{B_6}\) ; \(\hat{A_1};\hat{B_5}\) ; \(\hat{A_3};\hat{B_7}\); \(\hat{A_4};\hat{B_8}\)

Các cặp góc trong cùng phía là: \(\hat{A_1};\hat{B_6}\) ; \(\hat{A_4};\hat{B_7}\)

Các góc ngoài cùng phía là: \(\hat{A_3};\hat{B_8}\) ; \(\hat{A_2};\hat{B_5}\)

Các góc so le ngoài là: \(\hat{A_2};\hat{B_8}\) ; \(\hat{A_3};\hat{B_5}\)

voi x<0 suy ra :x<0,x+26<0,x-12<0 suy ra |x|=-x,|x+26|=-26-x,|x-12|=12-x

→P=-x+(-26-x)+12-x

→ P=-x-26-x+12-x=-3x-26+12=-3x-14

gi sai de roi

sai j z bạn bạn hông bít lm í đúng đề gùi . bài này là tìm giá trị nhỏ nhất

\(\left\{{}\begin{matrix}\left(\dfrac{1}{13}x-7\right)^8\ge0\\\left(\dfrac{1}{17}y-7\right)^6\ge0\end{matrix}\right.\Rightarrow\left(\dfrac{1}{13}x-7\right)^8+\left(\dfrac{1}{17}y-7\right)^6\ge0\)

Mà \(\left(\dfrac{1}{13}x-7\right)^8+\left(\dfrac{1}{17}y-7\right)^6=0\)

\(\Rightarrow\left\{{}\begin{matrix}\left(\dfrac{1}{13}x-7\right)^8=0\\\left(\dfrac{1}{17}y-7\right)^6=0\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=91\\y=119\end{matrix}\right.\)

Vậy \(x=91,y=119\)