\(\frac{1}{2}\)+\(\frac{1}{4}\)+\(\frac{1}{8}\)+...+\(\frac{1}{2^n}\)=\(\frac{2^n-1}{2^n}\)
1) \(\frac{1}{\cos x}+\frac{1}{\sin2x}=\frac{2}{\sin4x}\)
2) \(\cos3x\cdot\tan5x=\sin7x\)
3) \(\tan5x\cdot\tan2x=1\)
4) \(4\cos x-2\cos2x-\cos4x=1\)
5) \(\sin\left(2x+\frac{5\pi}{2}\right)-2\cos\left(x-\frac{7\pi}{2}\right)=1+2\sin x\)
6) \(\sin^22x-\cos^28x=\sin\left(\frac{17\pi}{2}+10x\right)\)
7) \(8\cos x=\frac{\sqrt{3}}{\sin x}+\frac{1}{\cos x}\)
Giải các Phương trình sau
a) \(sin^4\frac{x}{2}+cos^4\frac{x}{2}=\frac{1}{2}\)
b) \(sin^6x+cos^6x=\frac{7}{16}\)
c) \(sin^6x+cos^6x=cos^22x+\frac{1}{4}\)
d) \(tanx=1-cos2x\)
e) \(tan(2x+\frac\pi3).tan(\frac\pi3-x)=1\)
f) \(tan(x-15^o).cot(x+15^o)=\frac{1}{3}\)
12+32+52+ ... +(2n - 1)2= \(\frac{n\left(4n^2-1\right)}{3}\)
giải các pt
a) \(\sqrt{3}sinx+cosx=\frac{1}{cosx}\)
b) \(-\frac{1}{2}tan^2x+\frac{2}{cosx}-\frac{5}{2}=0\)
Giải các phương trình sau
1. \(sinx.cos\frac{\pi}{8}=\frac{1}{2}\)voi x\(\in\)\(\left[-\frac{3\pi}{2};\pi\right]\)
2. \(sinx.cos\frac{\pi}{8}+cos.sin\frac{\pi}{8}=\frac{1}{2}\)voi x\(\in\)\(\left[-\frac{\pi}{2};2\pi\right]\)
3. \(sin\left(\frac{\pi}{3}-2x\right).cos\left(\frac{x}{3}+\frac{\pi}{6}\right)=0\) voi x\(\in\)\(\left[-\frac{\pi}{3};\frac{5\pi}{3}\right]\)
giải giúp e câu này với ạ
1) \(\sin^2x-\sin x=2\cos^2x\)
2) \(2\sin^2x+\left(1-\sqrt{3}\right)\cos\left(\frac{5pi}{2}-x\right)-\sin\frac{pi}{3}=0\)
3) \(\cos\left(3x+\frac{pi}{4}\right)=\cos\frac{pi}{8}\)
giải các pt
a) \(cos\frac{4x}{3}=cos^2x\)
b) \(cos\frac{8x}{3}=cos^2\frac{2x}{3}\)
c) \(2cos^2\frac{3x}{5}+1=3cos\frac{4x}{5}\)
d) \(cos^2x+\frac{1}{cos^2x}+2=2cosx+\frac{2}{cosx}\)
1.2.3+2.3.4+3.4.5+...+n(n+1)(n+2)=\(\frac{n\left(n+1\right)\left(n+2\right)\left(n+3\right)}{4}\)