Giải hộ mình nha ai giải đc mình tick >3 lần
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Answer:
\(\sin x+4\cos x=2+\sin2x\)
\(\Leftrightarrow\sin x-2+4\cos x-2\sin x\cos x=0\)
\(\Leftrightarrow\sin x-2+2\cos x\left(2-\sin x\right)=0\)
\(\Leftrightarrow\left(\sin x-2\right)\left(1-2\cos x\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}\sin x=2\text{(Loại)}\\\cos x=\frac{1}{2}\end{cases}}\)
\(\Leftrightarrow x=\pm\frac{\text{π}}{3}+k2\text{π}\left(k\inℤ\right)\)
Nam is 16 years old . He is a student . He goes to school from Monday to Friday . Every day , his class starts at 7 o'clock and finishes at 11.30 . He likes english very much . he has it on monday , wednesday and thursday . He doesn't have classes on saturday and sunday . On these days , he stays at home . He does his homework , watches TV and listen to music .
nam is 16 yesrs old. he is a studen.he go to schools .....................
\(D=\frac{3}{11\cdot16}+\frac{3}{16\cdot21}+\frac{3}{21\cdot26}+....+\frac{3}{61\cdot66}\)
\(\frac{5}{3}D=\frac{5}{3}\left(\frac{3}{11\cdot16}+\frac{3}{16\cdot21}+\frac{3}{21\cdot26}+.....+\frac{3}{61\cdot66}\right)\)
\(\frac{5}{3}D=\frac{5}{11\cdot16}+\frac{5}{16\cdot21}+\frac{5}{21\cdot26}+....+\frac{5}{61\cdot66}\)
\(\frac{5}{3}D=\frac{1}{11}-\frac{1}{16}+\frac{1}{16}-\frac{1}{21}+\frac{1}{21}-\frac{1}{26}+....+\frac{1}{61}-\frac{1}{66}\)
\(\frac{5}{3}D=\frac{1}{11}-\frac{1}{66}\)
\(\frac{5}{3}D=\frac{5}{66}\)
\(D=\frac{5}{66}:\frac{5}{3}=\frac{5}{66}\cdot\frac{6}{5}=\frac{1}{11}\)
D = 3/11.16 + 3/16.21 + 3/21.26 + ...... + 3/61.66
D = \(\frac{3}{5}\) . ( \(\frac{5}{11.16}\)+ \(\frac{5}{16.21}\)+......+\(\frac{5}{61.66}\) )
D = \(\frac{3}{5}\). ( \(\frac{1}{11}\)- \(\frac{1}{16}\) + \(\frac{1}{16}\)- \(\frac{1}{21}\)+ ......... + \(\frac{1}{61}\)- \(\frac{1}{66}\))
D =\(\frac{3}{5}\). ( \(\frac{1}{11}\)- \(\frac{1}{66}\))
D = \(\frac{3}{5}\). \(\frac{5}{66}\)
D = \(\frac{1}{22}\)
# HOK TỐT #
I -X I < 5
=> -X < + 5
=> X = + 4 ; 3 ; 2;1;0 ( CÔNG TRỪ HẾT NHA MÌNH QUÊN MẤT