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a: \(125\left(19-135\right)-135\left(19-125\right)\)
\(=125\cdot19-125\cdot135-135\cdot19+135\cdot125\)
\(=125\cdot19-135\cdot19\)
\(=19\left(125-135\right)=-10\cdot19=-190\)
b: \(\left(-125\right)\left(135-19\right)-135\left(19-135\right)\)
\(=-125\cdot135+125\cdot19-135\cdot19+135^2\)
\(=135^2-135\cdot125+125\cdot19-135\cdot19\)
\(=135\left(135-125\right)+19\left(125-135\right)\)
\(=135\cdot10-19\cdot10\)
\(=116\cdot10=1160\)
c: \(125\left(19-135\right)+135\left(125-19\right)\)
\(=125\cdot19-125\cdot135+135\cdot125-135\cdot19\)
\(=125\cdot19-135\cdot19\)
\(=19\left(125-135\right)=19\cdot\left(-10\right)=-190\)
d: \(146\left(46-259\right)+259\left(146-46\right)\)
\(=146\cdot46-146\cdot259+259\cdot146-259\cdot46\)
\(=146\cdot46-259\cdot46\)
\(=46\left(146-259\right)\)
\(=46\cdot\left(-113\right)=-5198\)
e: \(195\left(17-185\right)-185\left(17-185\right)\)
\(=195\cdot17-195\cdot185-185\cdot17+185^2\)
\(=\left(195\cdot17-185\cdot17\right)-\left(195\cdot185-185^2\right)\)
\(=17\left(195-185\right)-185\left(195-185\right)\)
\(=10\left(17-185\right)=-168\cdot10=-1680\)
g: \(\left(-146\right)\left(19-156\right)+156\left(19-146\right)\)
\(=-146\cdot19+146\cdot156+156\cdot19-156\cdot146\)
\(=156\cdot19-146\cdot19=19\left(156-146\right)=190\)
h: \(\left(-243\right)\left(25-763\right)+763\left(25-243\right)\)
\(=-243\cdot25+243\cdot763+763\cdot25-763\cdot243\)
\(=763\cdot25-243\cdot25\)
\(=25\left(763-243\right)=520\cdot25=13000\)
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Đặt \(A=\frac{1}{2}+\frac{1}{2^2}+\frac{1}{2^3}+...+\frac{1}{2^{100}}\)
\(\Rightarrow2A=1+\frac{1}{2}+\frac{1}{2^2}+...+\frac{1}{2^{99}}\)
\(2A-A=\left(1+\frac{1}{2}+\frac{1}{2^2}+...+\frac{1}{2^{99}}\right)-\left(\frac{1}{2}+\frac{1}{2^2}+...+\frac{1}{2^{99}}+\frac{1}{2^{100}}\right)\)
\(A=1-\frac{1}{2^{100}}\)
\(A=\frac{2^{100}-1}{2^{100}}\)
Tham khảo nhé~
\(A=\frac{1}{2}+\frac{1}{2^2}+\frac{1}{2^3}+....+\frac{1}{2^{100}}\)
\(\Rightarrow\)\(2A=1+\frac{1}{2}+\frac{1}{2^2}+...+\frac{1}{2^{99}}\)
\(\Rightarrow\)\(2A-A=\left(1+\frac{1}{2}+\frac{1}{2^2}+...+\frac{1}{2^{99}}\right)-\left(\frac{1}{2}+\frac{1}{2^2}+\frac{1}{2^3}+...+\frac{1}{2^{100}}\right)\)
\(\Rightarrow\)\(A=1-\frac{1}{2^{100}}\)
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Để 1x5y chia hết cho 2 thì y = 0 , 2 , 4 , 6 , 8
Để 1x5y chia hết cho 5 thì y = 0 , 5
=> y = 0
Để 1x5y chia hết cho 3 thì 1 + x + 5 + 0 = 6+ x chia hết cho 3
=> x = 0 , 3 ,6 ,9
Để 1x5y chia hết cho 6 thì 1 + x + 5 + 0 = 6+x chia hết cho 6
=> x = 0 ; 6
Để 1x5y chia hết cho 9 thì 1 + x + 5 + 0 = 6 + x chia hết cho 9
=> x = 3
=> Ko tồn tại x
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Ta có: 4x^3=4x
Suy ra: 4x^3-4x=0
Suy ra: 4x(x^2-1)=0
Suy ra: 4x=0 nên x=0
x^2-1=0 nên x^2=1 nên x=1 hoặc -1
KL: x thuộc {1;-1;0}
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: ( 9/4 + 16/5 + 25/6 ) - ( 5/4 - 14/5 + 47/8 ) =0. 78125
Câu hỏi tương tự Đọc th\(\left(\frac{9}{4}+\frac{16}{5}+\frac{25}{6}\right)-\left(\frac{5}{4}-\frac{14}{5}+\frac{47}{8}\right)\)
\(=\frac{9}{4}+\frac{16}{5}+\frac{25}{6}-\frac{5}{4}+\frac{14}{5}-\frac{47}{8}\)
\(=\left(\frac{9}{4}-\frac{5}{4}\right)+\left(\frac{16}{5}+\frac{14}{5}\right)+\left(\frac{25}{6}-\frac{47}{8}\right)\)
\(=1+6-\frac{41}{24}\)
\(=7-\frac{41}{24}=\frac{127}{24}\)
a) 127 - 2(-2x + 4)² = -1
2(-2x + 4)² = 127 + 1
2(-2x + 4)² = 128
(-2x + 4)² = 128 : 2
(-2x + 4)² = 64
-2x + 4 = 8 hoặc -2x + 4 = -8
*) -2x + 4 = 8
-2x = 8 - 4
-2x = 4
x = 4 : (-2)
x = -2
*) -2x + 4 = -8
-2x = -8 - 4
-2x = -12
x = -12 : (-2)
x = 6
b) -6² - 3.(-4 - x)³ = -39
3(-4 - x)³ = -6² + 39
3(-4 - x)³ = -36 + 39
3(-4 - x)³ = 3
(-4 - x)³ = 3 : 3
(-4 - x)³ = 1
(-4 - x)³ = 1³
-4 - x = 1
x = -4 - 1
x = -5
c) (-7x - 35).(2x² - 32) = 0
-7x - 35 = 0 hoặc 2x² - 32 = 0
*) -7x - 35 = 0
-7x = 0 + 35
-7x = 35
x = 35 : (-7)
x = -5
*) 2x² - 32 = 0
2x² = 0 + 32
2x² = 32
x² = 32 : 2
x² = 16
x = -4; x = 4
Vậy x = -5; x = -4; x = 4
d) (2018 + 2x)(4x² + 8) = 0
2018 + 2x = 0 (do 4x² + 8 > 0)
2x = 0 - 2018
2x = -2018
x = -2018 : 2
x = -1014
e) -145 - 4(3 - 2x)² = -245
4(3 - 2x) = -145 + 245
4(3 - 2x) = 100
3 - 2x = 100 : 4
3 - 2x = 25
2x = 3 - 25
2x = -22
x = -22 : 2
x = -11
g) 4(-x + 1)³ - (-5)² = -525
4(-x + 1)³ - 25 = -525
4(-x + 1)³ = -525 + 25
4(-x + 1)³ = -500
(-x + 1)³ = -500 : 4
(-x + 1)³ = -125
(-x + 1)³ = (-5)³
-x + 1 = -5
-x = -5 - 1
-x = -6
x = 6
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