\(\left(\dfrac{-5}{24}+0,75+\dfrac{7}{12}\right):\left(-2\dfrac{1}{4}\right)\\ =\left(\dfrac{-5}{24}+\dfrac{3}{4}+\dfrac{7}{12}\right):\dfrac{-9}{4}\\ =\dfrac{9}{8}.\dfrac{-4}{9}\\ =\dfrac{-1}{2}\)

\(B=\frac{270}{13}+\frac{21}{2}+\frac{100}{7}+\frac{1638}{25}\)

\(B=111,07\)

Mình đang cần hơi gấp

=\(\frac{389}{2275}\)

\(\left(x^2-\dfrac{1}{3}\right)\left(x^4+\dfrac{1}{3}x^2+\dfrac{1}{9}\right)=x^6-\dfrac{1}{27}\)

\(B^3=4+3\sqrt[3]{\left(2+\sqrt[]{5}\right)\left(2-\sqrt[]{5}\right)}\left(\sqrt[3]{2+\sqrt[]{5}}+\sqrt[3]{2-\sqrt[]{5}}\right)\)

\(\Leftrightarrow B^3=4-3B\)

\(\Leftrightarrow B^3+3B-4=0\)

\(\Leftrightarrow\left(B-1\right)\left(B^2+B+4\right)=0\)

\(\Leftrightarrow B=1\)

=3/4*4/5*...*99/100

=3/100

15.141+59.15=2115+885=3000

20-[30-(5-1²)]=20-[30-(5-1)]=20-[30-4)]=20-26=.....chỗ này đề bài sai nha bn

20-[30-(5-1^2)]=20-[30-(5-1)^2]=20-[30-4^2]=20-[30-16]=20-14=6

\(B=1+7+7^2+7^3+...+7^{150}\)

\(7B=7.\left(1+7+7^2+7^3+...+7^{150}\right)\)

\(7B=7+7^2+7^3+7^4+...+7^{151}\)

\(7B-B=\left(7+7^2+7^3+7^4+...+7^{151}\right)-\left(1+7+7^2+7^3+...+7^{150}\right)\)

\(6B=\left(7^{151}-1\right)\)

\(B=\left(7^{151}-1\right):6\)

  B      = 1 + 7 +  7² + ...+ 7¹⁵⁰

7.B     =      7  + 7²+.....+ 7¹⁵⁰ + 7¹⁵¹

7B - B =     7¹⁵¹  - 1

6B      =     7¹⁵¹ - 1

   B     = \(\dfrac{7^{151}-1}{6}\)

\(B=\frac{1-tana}{\frac{1}{sin^2a}}=\frac{1-tana}{1+cot^2a}=\frac{1-tana}{1+\frac{1}{tan^2a}}=\frac{1-\frac{7}{24}}{1+\left(\frac{7}{24}\right)^2}=...\)