a: Ta có: \(\hat{CAD}=\hat{ADE}\left(=55^0\right)\)

mà hai góc này là hai góc ở vị trí so le trong

nên AC//DE

b: ta có: \(\hat{AFB}=\hat{ADC}\left(=45^0\right)\)

mà hai góc này là hai góc ở vị trí đồng vị

nên BE//CD

Bài 4:

Ta có: \(\hat{M_2}=\hat{N_2}\left(=60^0\right)\)

mà hai góc này là hai góc ở vị trí đồng vị

nên a//b

Bài 3:

a//b

a⊥BA

Do đó: b⊥BA

=>\(\hat{ABC}=90^0\)

AD//BC

=>\(\hat{ADC}+\hat{DCB}=180^0\)

=>\(\hat{ADC}=180^0-110^0=70^0\)

Bài 2:

a: \(-\frac35+\frac{-2}{5}:x=\frac13\)

=>\(-\frac25:x=\frac13+\frac35=\frac{5}{15}+\frac{9}{15}=\frac{14}{15}\)

=>\(x=-\frac25:\frac{14}{15}=-\frac25\cdot\frac{15}{14}=-\frac37\)

b: \(0,2+\left|x-1,3\right|=1,5\)

=>|x-1,3|=1,5-0,2=1,3

=>\(\left[\begin{array}{l}x-1,3=1,3\\ x-1,3=-1,3\end{array}\right.\Rightarrow\left[\begin{array}{l}x=2,6\\ x=0\end{array}\right.\)

c: \(\left(\frac37-2x\right)^2=\frac49\)

=>\(\left[\begin{array}{l}\frac37-2x=\frac23\\ \frac37-2x=-\frac23\end{array}\right.\Rightarrow\left[\begin{array}{l}2x=\frac37-\frac23=\frac{9}{21}-\frac{14}{21}=-\frac{5}{21}\\ 2x=\frac37+\frac23=\frac{9}{21}+\frac{14}{21}=\frac{23}{21}\end{array}\right.\)

=>\(\left[\begin{array}{l}x=-\frac{5}{21}:2=-\frac{5}{42}\\ x=\frac{23}{21}:2=\frac{23}{42}\end{array}\right.\)

d: \(2^{x}+2^{x+3}=144\)

=>\(2^{x}+2^{x}\cdot2^3=144\)

=>\(2^{x}\left(1+2^3\right)=144\)

=>\(2^{x}\cdot9=144\)

=>\(2^{x}=\frac{144}{9}=16=2^4\)

=>x=4

Bài 1:

a: \(\frac{14}{57}+\frac{29}{23}-\frac{71}{57}+\frac{-6}{23}\)

\(=\left(\frac{14}{57}-\frac{71}{57}\right)+\left(\frac{29}{23}-\frac{6}{23}\right)\)

\(=\frac{-57}{57}+\frac{23}{23}=-1+1=0\)

b: \(\frac{5}{12}\cdot\left(-\frac34\right)+\frac{7}{12}\left(-\frac34\right)\)

\(=-\frac34\left(\frac{5}{12}+\frac{7}{12}\right)=-\frac34\cdot\frac{12}{12}=-\frac34\)

d: \(\left(-\frac{3}{11}:\frac{5}{22}\right)\cdot\left(-\frac{15}{3}:\frac{26}{3}\right)\)

\(=-\frac{3}{11}\cdot\frac{22}{5}\cdot\left(_{}-5\right)\cdot\frac{3}{26}=-\frac35\cdot\left(-5\right)\cdot2\cdot\frac{3}{26}=3\cdot2\cdot\frac{3}{26}=\frac{9}{13}\)

f: \(\frac{9^{15}\cdot8^{11}}{3^{29}\cdot16^8}=\frac{3^{30}}{3^{29}}\cdot\frac{2^{33}}{2^{32}}=3\cdot2=6\)

Bài 3:

a: \(A=3^2\cdot\frac{1}{243}\cdot81^2\cdot\frac{1}{3^3}\)

\(=\frac{9}{243}\cdot81\cdot81\cdot\frac{1}{27}\)

\(=\frac{1}{27}\cdot81\cdot3=3\cdot3=9\)

b: \(B=\left(4\cdot2^5\right):\left(2^3\cdot\frac{1}{16}\right)\)

\(=2^2\cdot2^5:\left(\frac{2^3}{16}\right)=2^7:\frac12=2^7\cdot2=2^8=256\)

Bài 2:

a: \(A=\left(3^2\right)^2-\left(-2^3\right)^2-\left(-5^2\right)^2\)

\(=3^4-2^6-\left(-25\right)^2\)

=81-64-625

=17-625

=-608

b: \(B=2^3+3\cdot\left(\frac12\right)^0\cdot\left(\frac12\right)^2\cdot4+\left\lbrack\left(-2\right)^2:\frac12\right\rbrack:8\)

\(=8+3\cdot1\cdot\frac14\cdot4+4\cdot\frac28\)

=8+3+1

=11+1

=12

Bài 1:

a: \(\left(\frac23\right)^3\cdot\left(-\frac34\right)^2\cdot\left(-1\right)^5:\left(\frac25\right)^2\cdot\left(-\frac{5}{12}\right)^2\)

\(=\frac{2^3}{3^3}\cdot\frac{3^2}{4^2}\cdot\left(-1\right):\frac{4}{25}\cdot\frac{25}{144}\)

\(=\frac{2^3}{2^4}\cdot\frac13\cdot\left(-1\right)\cdot\frac{25}{4}\cdot\frac{25}{144}=\frac16\cdot\left(-1\right)\cdot\frac{625}{576}=\frac{-625}{3456}\)

b:Sửa đề: \(\frac{\left(6^6+6^3\cdot3^3+3^6\right)}{-73}\)

\(=\frac{3^6\cdot2^6+3^6\cdot2^3+3^6}{-73}\)

\(=\frac{3^6\left(2^6+2^3+1\right)}{-73}=\frac{3^6\cdot73}{-73}=-3^6=-729\)

a: \(\frac{x-100}{24}+\frac{x-98}{26}+\frac{x-96}{28}=3\)

=>\(\left(\frac{x-100}{24}-1\right)+\left(\frac{x-98}{26}-1\right)+\left(\frac{x-96}{28}-1\right)=0\)

=>\(\frac{x-124}{24}+\frac{x-124}{26}+\frac{x-124}{28}=0\)

=>\(\left(x-124\right)\left(\frac{1}{24}+\frac{1}{26}+\frac{1}{28}\right)=0\)

=>x-124=0

=>x=124

b: \(\frac{x-1}{65}+\frac{x-3}{63}=\frac{x-5}{61}+\frac{x-7}{59}\)

=>\(\left(\frac{x-1}{65}-1\right)+\left(\frac{x-3}{63}-1\right)=\left(\frac{x-5}{61}-1\right)+\left(\frac{x-7}{59}-1\right)\)

=>\(\frac{x-66}{65}+\frac{x-66}{63}=\frac{x-66}{61}+\frac{x-66}{59}\)

=>\(\left(x-66\right)\left(\frac{1}{65}+\frac{1}{63}-\frac{1}{61}-\frac{1}{59}\right)=0\)

=>x-66=0

=>x=66

c: \(\frac{x-28-124}{2011}+\frac{x-124-2011}{28}+\frac{x-2011-28}{124}=3\)

=>\(\left(\frac{x-28-124}{2011}-1\right)+\left(\frac{x-124-2011}{28}-1\right)+\left(\frac{x-28-2011}{124}-1\right)=0\)

=>x-28-124-2011=0

=>x=2011+124+28

=>x=2163

Bài 8:

Chu vi đáy là:

3,5+3,5+3+6=7+9=16(cm)

Diện tích xung quanh là: \(16\cdot11,5=184\left(\operatorname{cm}^2\right)\)

Bài 9:

Diện tích đáy là:

\(S=\frac12\cdot7\cdot24=12\cdot7=84\left(m^2\right)\)

Thể tích của khối bê tông là:

\(84\cdot22=1848\left(m^3\right)\)

Số tiền phải trả là:

\(1848\cdot2500000=4620000000\) (đồng)

Cách 1: ta có: \(\hat{yAB}+\hat{y^{\prime}AB}=180^0\) (hai góc kề bù)

=>\(\hat{y^{\prime}AB}=180^0-105^0=75^0\)

ta có: \(\hat{y^{\prime}AB}=\hat{x^{\prime}Bz}\left(=75^0\right)\)

mà hai góc này là hai góc ở vị trí đồng vị

nên Ay//Bz

=>yy'//Bz

Cách 2:

Ta có: \(\hat{x^{\prime}Bz}+\hat{xBz}=180^0\) (hai góc kề bù)

=>\(\hat{xBz}=180^0-75^0=105^0\)

Ta có: \(\hat{xBz}=\hat{yAB}\left(=105^0\right)\)

mà hai góc này là hai góc ở vị trí so le trong

nên Ay//Bz

=>yy'//Bz