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a, =\(3^4+2^5=81+32=113\)
b, =\(3.\left(4^2-2.3\right)=3.\left(16-6\right)=3.10=30\)
c, =\(\dfrac{2^{12}.3^4.3^{10}}{2^{12}.3^{12}}=\dfrac{2^{12}.3^{14}}{2^{12}.3^{12}}=3^2=9\)
d, =\(\dfrac{3^2.7^2.2.7.5^3}{5^3.7^3.2.3}=3\)
e, =\(\dfrac{3^6.5^3.2^8.5^4.2^2.3^4}{2^{10}.3^{10}.5^5}=\dfrac{3^{10}.2^{10}.5^7}{2^{10}.3^{10}.5^5}=5^2=25\)
g, =\(\dfrac{2^5.\left(2^8+1\right)}{2^2.\left(2^8+1\right)}=\dfrac{2^5}{2^2}=2^3=8\)
a)
x= 43
b) 2X-12=8
2X =8+12
2X=20
X=20:2
x =10
c)45:(3X-17)=32
45 : (3X-17)=9
3X-17=45:9
3X-17=5
3X=5+17
3X=22
x=22:3
x= 7,33
d)(2X-8)x2=24
( 2X-8)x2 =16
2X-8 =16:2
2X-8 =8
2X =8+8
2X =16
x =16:2
X =8
Đúng thì tk nếu sai thì thôi
Làm ẩu ^^
a) \(A=1+3+3^2+.....+3^{10}⋮4\)
\(=\left(1+3\right)+\left(3^2+3^3\right)+.......+\left(3^9+3^{10}\right)\)
\(=\left(1+3\right)+\left(3^2\cdot1+3^2\cdot3\right)+.....+\left(3^9\cdot1+3^9\cdot3\right)\)
\(=\left(1+3\right)+3^2\left(1+3\right)+....+3^9\left(1+3\right)\)
\(=4\cdot1+3^2\cdot4+.......+3^9\cdot4\)
\(=4\cdot\left(1+3^2+.....+3^9\right)⋮4\)
Do đó A \(⋮\) 4
b) \(B=16^5+2^{15}⋮33\)
Ta có \(B=16^5+2^{15}\)
\(=\left(2^4\right)^5+2^{15}\)
\(=2^{20}+2^{15}\)
\(=2^{15}\cdot2^5+2^{15}\cdot1\)
\(=2^{15}\cdot\left(2^5+1\right)\)
\(=2^5\cdot\left(32+1\right)\)
\(=2^{15}\cdot33⋮33\)
Do đó \(B⋮33\)
Ta có:
\(A=1^{11}+2^{11}+3^{11}+...+9^{11}\)
\(1^{11}+9^{11}\equiv1^{11}+\left(-1\right)^{11}\left(mod10\right)\equiv0\left(mod10\right)\)
\(2^{11}+8^{11}\equiv2^{11}+\left(-2\right)^{11}\left(mod10\right)\equiv0\left(mod10\right)\)
\(3^{11}+7^{11}\equiv3^{11}+\left(-3\right)^{11}\left(mod10\right)\equiv0\left(mod10\right)\)
\(4^{11}+6^{11}\equiv4^{11}+\left(-4\right)^{11}\left(mod10\right)\equiv0\left(mod10\right)\)
\(5^{11}⋮5\)
Do đó \(A⋮5\).
\(1^{11}+8^{11}\equiv1^{11}+\left(-1\right)^{11}\left(mod9\right)\equiv0\left(mod9\right)\)
\(2^{11}+7^{11}\equiv2^{11}+\left(-2\right)^{11}\left(mod9\right)\equiv0\left(mod9\right)\)
\(3^{11}+6^{11}\equiv3^{11}+\left(-3\right)^{11}\left(mod9\right)\equiv0\left(mod9\right)\)
\(4^{11}+5^{11}\equiv4^{11}+\left(-4\right)^{11}\left(mod9\right)\equiv0\left(mod9\right)\)
\(9^{11}⋮9\)
suy ra \(A⋮9\).
Mà \(\left(5,9\right)=1\)nên \(A\)chia hết cho \(5.9=45\).
Ta có đpcm.
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\(a)\) Ta có :
\(A=\frac{1}{2}+\frac{1}{2^2}+\frac{1}{2^3}+...+\frac{1}{2^{100}}\)
\(2A=1+\frac{1}{2}+\frac{1}{2^2}+...+\frac{1}{2^{99}}\)
\(2A-A=\left(1+\frac{1}{2}+\frac{1}{2^2}+...+\frac{1}{2^{99}}\right)-\left(\frac{1}{2}+\frac{1}{2^2}+\frac{1}{2^3}+...+\frac{1}{2^{100}}\right)\)
\(A=1-\frac{1}{2^{100}}< 1\)
Vậy \(A< 1\)
Chúc bạn học tốt ~
a) 38.52+38.49+76.13
=38.25+38.49+76.13
=[(25+49).38]+(76.13)
= tự tính
Bài 1 :
a, Ta có : \(\left(-123\right)+\left|-13\right|+\left(-7\right)\)
= \(\left(-123\right)+13+\left(-7\right)=\left(-117\right)\)
b, Ta có : \(\left|-10\right|+\left|45\right|+\left(-\left|-455\right|\right)+\left|-750\right|\)
= \(10+45-455+750=350\)
c, Ta có : \(-\left|-33\right|+\left(-15\right)+20-\left|45-40\right|-57\)
= \(\left(-33\right)+\left(-15\right)+20-5-57=-90\)