Làm tính chia:
(Viết ở dạng rút gọn đơn giản nhất)
\(\left(4x+4\times4\right):2\times2\)
>3 :) Nghé thăm
1. Rút gọn biểu thức \(P=cos^4x-sin^4x\)
\(A.P=cos2x\) \(B.P=\dfrac{3}{4}+\dfrac{1}{4}cos4x\) \(C.P=\dfrac{1}{4}+\dfrac{3}{4}cos4x\) \(D.P=\dfrac{3}{4}-\dfrac{1}{4}cos4x\)
2.Đơn giản biểu thức \(D=sin\left(\dfrac{5\pi}{2}-\alpha\right)+cos\left(13\pi+\alpha\right)-3sin\left(\alpha-5\pi\right)\)
\(A.3sina-2cosa\) \(B.3sina\) \(C.-3sina\) \(D.2cosa+3sina\)
Trắc nghiệm nhưng mong mn trình bày bài làm giúp em để tham khảo với ạ. Em cảm ơn
1.Ý A
\(P=cos^4x-sin^4x=\left(cos^2x-sin^2x\right)\left(cos^2x+sin^2x\right)=cos2x\)
2. Ý B
\(D=sin\left(\dfrac{5\pi}{2}-\alpha\right)+cos\left(13\pi+\alpha\right)-3sin\left(\alpha-5\pi\right)\)
\(=sin\left(2\pi+\dfrac{\pi}{2}-\alpha\right)+cos\left(\pi+\alpha+12\pi\right)-3sin\left(\alpha+\pi-6\pi\right)\)
\(=sin\left(\dfrac{\pi}{2}-\alpha\right)+cos\left(\pi+\alpha\right)-3sin\left(\alpha+\pi\right)\)
\(=cos\alpha-cos\alpha+3sin\alpha=3sin\alpha\)
Tính
a)\(A=\frac{\left(3\times2^{20}+7\times2^{19}\right)\times52}{\left(13\times8^4\right)^2}\)
b)\(B=\frac{2^{19}\times27^3+15\times4^9\times9^4}{6^9\times2^{10}+12^{10}}\)
Tính
\(\frac{\left(3\times4\times2^{16}\right)^2}{11\times2^{13}\times4^{11}-16^9}\)
Các bạn giải hộ mình với!!!
\(\frac{\left(3.4.2^{16}\right)^2}{11.2^{13}.4^{11}-16^9}\)
\(=\frac{\left(3.2^2.2^{16}\right)^2}{11.2^{13}.\left(2^2\right)^{11}-\left(2^4\right)^9}\)
\(=\frac{\left(3.2^{18}\right)^2}{11.2^{13}.2^{22}-2^{36}}\)
\(=\frac{3^2.2^{36}}{2^{35}.\left(11-2\right)}\)
\(=\frac{3^2.2}{11-2}\)
\(=2\)
Tìm x biết:
\(\left(\left(4\times4+1\right)^{\sqrt{\frac{3}{2}\times2}}\right)\times x=\sqrt{6400}+\sqrt{6400}\times2\)
\(\left[\left(4.4+1\right)\sqrt{\frac{3}{2}.2}\right].x=\sqrt{6400}+\sqrt{6400}.2\)
\(\Rightarrow\left[17.\sqrt{3}\right].x=80+80.2\)
\(\Rightarrow17\sqrt{3}.x=240\)
\(\Rightarrow x=\frac{240}{17\sqrt{3}}\)
Tính S = \(\frac{5\times2^{30}\times6^2\times3^{15}-2^3\times8^9\times3^{17}\times21}{21\times2^{29}\times3^{16}\times4-2^{29}\times\left(3^4\right)^5}\)
Ta có : S = \(\frac{5.2^{30}.6^3.3^{15}-2^3.8^9.3^{17}.21}{21.2^{29}.3^{16}.4-2^{29}.\left(3^4\right)^5}=\frac{5.2^{30}.\left(2.3\right)^3.3^{15}-2^3.\left(2^3\right)^9.3^{17}.3.7}{3.7.2^{29}.3^{16}.2^2-2^{29}.3^{20}}=\frac{5.2^{33}.3^{18}-2^{30}.3^{18}.7}{3^{17}.7.2^{31}-2^{29}.3^{20}}\)
\(=\frac{2^{30}.3^{18}.\left(5.2^3-7\right)}{3^{17}.2^{29}.\left(7.2^2-3^3\right)}=2.3.33=198\)
Tính C=\(\frac{1}{1\times2\times3}+\frac{1}{2\times3\times4}+\frac{1}{3\times4\times5}+....+\frac{1}{n\times\left(n+1\right)\times\left(n+2\right)}\)
Bạn nào giúp mik nhớ viết cả cách giải cho mik nhé!!!!!!!!!!
\(C=\dfrac{5\times4^6\times9^4-3^9\times\left(-8\right)^4}{4\times2^{13}\times3^8+2\times8^4\times\left(-27\right)^3}\)
\(C=\dfrac{5\times2^{12}\times3^8-3^9\times2^{12}}{2^2\times2^{13}\times3^8+2\times2^{12}\times\left(-3^9\right)}=\dfrac{3^8\times2^{12}\times\left(5-3\right)}{2^{15}\times3^8+2^{13}\times\left(-3\right)^9}\)
\(=\dfrac{3^8\times2^{12}\times2}{2^{13}\times3^8\times\left(4-3\right)}=\dfrac{1}{1}=1\)
\(#PaooNqoccc\)
Tinh
\(\frac{\left(3\times4\times2^{16}\right)^2}{11\times2^{13}\times4^{11}-16^9}\)
\(=\dfrac{3^2\cdot2^{36}}{11\cdot2^{13}\cdot2^{22}-2^{36}}=\dfrac{3^2\cdot2^{36}}{2^{35}\cdot9}=2\)
Tính :
\(\dfrac{\left(3\times4\times2^{16}\right)^2}{11\times2^{13}\times4^{11}-16^9}\)
\(=\dfrac{3^2\cdot2^{36}}{11\cdot2^{35}-2^{36}}=\dfrac{3^2\cdot2^{36}}{2^{35}\left(11-2\right)}=2\)