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\(a^{2n}+b^{2n}\le0\Leftrightarrow a^{2n}+b^{2n}=0\Leftrightarrow a=b=0\)
a,\(\left(x-\frac{2}{5}\right)^{2010}+\left(y+\frac{3}{7}\right)^{468}\)< \(0\)
Vì \(\left(x-\frac{2}{5}\right)^{2010}\);\(\left(y+\frac{3}{7}\right)^{468}\)đều > \(0\)
=> \(\left(x-\frac{2}{5}\right)^{2010}=0\)
\(\left(y+\frac{3}{7}\right)^{468}=0\)
=> \(\left(x-\frac{2}{5}\right)^{2010}=0^{2010}\)
\(\left(y+\frac{3}{7}\right)^{468}=0^{468}\)
=> \(x-\frac{2}{5}=0\)
\(y-\frac{3}{7}=0\)
=> \(x=\frac{2}{5}\)
\(y=\frac{3}{7}\)
Vậy \(x=\frac{2}{5}\)\(y=\frac{3}{7}\)
5.(x - 1) + 6.(x - 2) = 5
5x - 5 + 6x - 12 = 5
11x - 17 = 5
11x = 5 + 17
11x = 22
x = 2
3.(x - 2) + 6.(x - 1) = 6
3x - 6 + 6x - 6 = 6
9x - 12 = 6
9x = 6 + 12
9x = 18
x = 2
5 ( x - 1 ) + 6 ( x - 2 ) = 5
<=> 5x - 5 + 6x - 12 = 5
<=> 11x = 22
<=> x = 2
Vậy x = 2
a,3x-3+6x-12=5
9x-15=5
9x=20
x=20/9
b,3x-6+6x-6=6
9x-12=6
9x=18
x=2
c,4x+4+5x+10=3x+20
9x+14=3x+20
9x-3x=6
6x=6
x=1
a) 3.(x-1) + 6.(x-2) = 5
3.x - 3 + 6.x - 12 = 5
9.x - 15 = 5
9.x = 5 + 15
9.x = 20
x = \(\frac{20}{9}\)
Vậy x = \(\frac{20}{9}\)
b) 3.(x-2) + 6.(x-1) = 6
3.x - 6 + 6.x - 6 = 6
9.x - 12 = 6
9.x = 6 + 12
9.x = 18
x = 18 : 9
x = 2
Vậy x = 2
c) 4.(x+1) + 5.(x+2) = 3.x +20
4.x +4 +5.x +10 = 3.x +20
9.x + 14 = 3.x +20
9.x - 3.x = 20 - 14
6.x = 6
x = 6 : 6
x = 1
Vậy x = 1
c) (x+1) + (x+2) + ... + (x+5) = 90
=> 5x + ( 1 + 2 + ... + 5 ) = 90
5x + 15 = 90
5x = 90 - 15
5x = 75
x = 75 : 5
x = 15
d) (x+1) + (x+2) + .... + (x+100) = 20150
=> 100x + ( 1+2+...+100 ) = 20150
100x + 5050 = 20150
100x = 20150 - 5050
100x = 15100
x = 15100 : 100
x = 151
Ta có : (x + 1) + (x + 2) + (x + 3) + (x + 4) + (x + 5) = 90
<=> x + x + x+ x + x + (1 + 2 + 3 + 4 + 5) = 90
<=> 5x + 15 = 90
=> 5x = 75
=> x = 15
a) 3 x (x + 1) + 4 x (x + 2) = 18
<=> 3x + 3 + 4x + 8 = 18
<=> 7x + 11 = 18
<=> 7x = 18 - 11
<=> 7x = 7
<=> x = 7 : 7 = 1
=> x = 1
b) 4 x (x + 1) + 7 x (2x + 3) = 61
<=> 4x + 4 + 14x + 21 = 61
<=> 18x + 25 = 61
<=> 18x = 61 - 25
<=> 18x = 36
<=> x = 36 : 18
<=> x = 2
=> x = 2
b, (y+1) + (y+2) + (y+3) + .... + (y+99) = 6138
(y+y+y+y+....+y) + (1+2+3+...+99) = 6138
99.y + 4950 = 6138
99.y = 6138 - 4950
99.y = 1188
y = 1188 : 99
x = 12
a) \(\left(y+1\right)+\left(y+4\right)+\left(y+7\right)+....+\left(y+28\right)=155155\)
\(\Rightarrow\left(y+y+...+y\right)+\left(1+4+7+...+28\right)=155155\)
\(\Rightarrow10x+145=155155\)
\(\Rightarrow10x=155010\)
\(\Rightarrow x=15501\)
Vậy x = 15501
b) \(\left(y+1\right)+\left(y+2\right)+..+\left(y+99\right)=6138\)
\(\Rightarrow\left(y+y+...+y\right)+\left(1+2+3+...+99\right)=6138\)
\(\Rightarrow99x+4950=6138\)
\(\Rightarrow99x=1188\)
\(\Rightarrow x=12\)
Vậy x = 12
\(\left(1+\frac{1}{2}\right)\times\left(1+\frac{1}{3}\right)\times\left(1+\frac{1}{4}\right)\times....\times\left(1+\frac{1}{98}\right)\times\left(1+\frac{1}{99}\right)\)
\(=\frac{3}{2}\times\frac{4}{3}\times\frac{5}{4}\times....\times\frac{99}{98}\times\frac{100}{99}\)
\(=\frac{3\times4\times5\times...\times99\times100}{2\times3\times4\times....\times98\times99}\)
\(=\frac{100}{2}=50\)
(1+1/2).(1+1/3).(1+1/4)....(1+1/98).(1+1/99)
=3/2.4/3.5/4...99/98.100/99
=3.4.5....99.100/2.3.4....98.99
=100/2
=50