Đoạn văn b ơi :33

b d b b c a

Question 1: B
Question 2: D
Question 3: B
Question 4: B
Question 5: C
Question 6: A

\(10+2x=45\div4^5\)

\(10+2x=45\div1024\)

\(10+2x=\dfrac{45}{1024}\)

\(2x=\dfrac{45}{1024}-10\)

\(2x=-\dfrac{10195}{1024}\)

\(x=-\dfrac{10195}{1024}:2=-\dfrac{10195}{2048}\)

9b: 

Kẻ OK vuông góc SA tại K

BD vuông góc AC

BD vuông góc SO

=>BD vuông góc (SAC)

=->BD vuông góc SA

mà OK vuông góc SA

nên SA vuông góc (BKD)

=>SA vuông góc BK; SA vuông góc KD

=>((SAB); (SAD))=(BK;KD)

ΔSAC vuông cân tại O nên OK=1/2SA=a/căn 3

ΔBKD cso KO=BO=OD=a/căn 3=1/2*BD

=>ΔBKD vuông tại K

=>góc BKD=90 độ

=>(SAB) vuông góc (SAD)

\(a,=\left(-\dfrac{1}{3}\right)^3=-\dfrac{1}{27}\\ b,=\left(-2\right)^6=2^6=64\\ c,=5^6:5^2=5^4=625\)

\(a,\left(-\dfrac{1}{3}\right)^2.\left(-\dfrac{1}{3}\right)=-\dfrac{1}{3}\)

\(b,\left(-2\right)^2.\left(-2\right)^4=\left(-2\right)^6\)

\(c,25^3:5^2=5^6:5^2=5^3\)

a.(-1/3)^2.(-1/3)=(-1/3)^3

b.(-2)^2.(-2)^4=(-2)^6

c.25^3:5^2=5^6:5^2=5^4

ht

(5/6+1/6)x4/5

= 1 x 4/5

=4/5

\(\dfrac{4}{5}\) x ( \(\dfrac{5}{6}\) + \(\dfrac{1}{6}\))

\(\dfrac{4}{5}\) x  1

\(\dfrac{4}{5}\)

\(a,\dfrac{-4}{5}+\dfrac{2}{7}-\dfrac{1}{5}-\dfrac{9}{7}=\left(\dfrac{-4}{5}-\dfrac{1}{5}\right)+\left(\dfrac{2}{7}-\dfrac{9}{7}\right)=-1+\left(-1\right)=-2\)

\(b,\dfrac{1}{12}-\left(\dfrac{1}{2}+\dfrac{7}{12}\right)=\dfrac{1}{12}-\left(\dfrac{6}{12}+\dfrac{7}{12}\right)=\dfrac{1}{12}-\dfrac{13}{12}=\dfrac{-12}{12}=-1\)

\(c,\dfrac{-12}{5}-\left(\dfrac{3}{5}-\dfrac{1}{8}\right)=\dfrac{-12}{5}-\left(\dfrac{24}{40}-\dfrac{5}{40}\right)=\dfrac{-12}{5}-\dfrac{19}{40}=\dfrac{-96}{40}-\dfrac{16}{40}=\dfrac{-100}{40}=\dfrac{-5}{2}\)

\(d,\dfrac{-5}{7}-\left(\dfrac{-7}{6}+\dfrac{2}{7}\right)+\dfrac{7}{-6}=\dfrac{-5}{7}+\dfrac{7}{6}-\dfrac{2}{7}+\dfrac{-7}{6}=\left(\dfrac{-5}{7}-\dfrac{2}{7}\right)+\left(\dfrac{7}{6}+\dfrac{-7}{6}\right)=-1\)

\(e,\dfrac{-6}{5}-\dfrac{2}{7}+\dfrac{1}{5}-\dfrac{5}{7}=\left(\dfrac{-6}{5}+\dfrac{1}{5}\right)+\left(\dfrac{-2}{7}-\dfrac{5}{7}\right)=-1+\left(-1\right)=-2\)

\(a,-\dfrac{4}{5}+\dfrac{2}{7}-\dfrac{1}{5}-\dfrac{9}{7}\)

\(=\dfrac{2}{7}-\dfrac{9}{7}-\dfrac{4}{5}-\dfrac{1}{5}\)

\(=-\dfrac{7}{7}-\dfrac{5}{5}\)

\(=-1-1=-2\)

\(b,\dfrac{1}{12}-\left(\dfrac{1}{2}+\dfrac{7}{12}\right)\)

\(=\dfrac{1}{12}-\dfrac{7}{12}-\dfrac{1}{2}\)

\(=-\dfrac{6}{12}-\dfrac{1}{2}=-1\)

\(c,-\dfrac{12}{5}-\left(\dfrac{3}{5}-\dfrac{1}{8}\right)\)

\(=-\dfrac{12}{5}-\dfrac{3}{5}+\dfrac{1}{8}\)

\(=-\dfrac{15}{5}+\dfrac{1}{8}\)

\(=-3+\dfrac{1}{8}=-\dfrac{23}{8}\)

\(d,-\dfrac{5}{7}-\left(-\dfrac{7}{6}+\dfrac{2}{7}\right)+\dfrac{7}{-6}\)

=\(-\dfrac{5}{7}+\dfrac{7}{6}-\dfrac{2}{7}-\dfrac{7}{6}\)

\(=-\dfrac{5}{7}-\dfrac{2}{7}\)

\(=-\dfrac{7}{7}=-1\)

\(e.-\dfrac{6}{5}-\dfrac{2}{7}+\dfrac{1}{5}-\dfrac{5}{7}\)

\(=-\dfrac{6}{5}+\dfrac{1}{5}-\dfrac{2}{7}-\dfrac{5}{7}\)

\(=\dfrac{5}{5}-\dfrac{7}{7}\)

\(=1-1=0\)