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2100=(210)10=102410>100010=10302100=(210)10=102410>100010=1030
2100=231.26.263=231.64.5127<231.125.6257=231.53.(54)7=231.531=10312100=231.26.263=231.64.5127<231.125.6257=231.53.(54)7=231.531=1031
1030<2100<10311030<2100<1031
vậy 21002100 có 31 chữ số.
1,=0 . [2017/2018+2018/2019]
=>0
2,TH1 x-3=0=>x=3
TH2 y-4=0=>y=4
3, -2/4 = -x/10 = 16/y
=>-1/2 = -x/10 = 16/y
=>-1/2 = -x/10 => -5/10 = -x/10 => x=5
-1/2 = 16/y => 16/-32 = 16/y => y = -32
a) 4.(-5)2+(-2)3.25
= 4.25+(-8).25
=25.[4+(-8)]
=25.(-4)
=-100
b)\(15\dfrac{3}{7}-\left(\dfrac{7}{15}+9\dfrac{4}{7}\right)\)
= \(15\dfrac{3}{7}-\dfrac{7}{15}-9\dfrac{4}{7}\)
= \(\left(15\dfrac{3}{7}-9\dfrac{4}{7}\right)-\dfrac{7}{15}\)
=\(\left(14\dfrac{10}{7}-9\dfrac{4}{7}\right)-\dfrac{7}{15}\)
=\(5\dfrac{1}{7}-\dfrac{7}{15}\)
=\(\dfrac{36}{7}-\dfrac{7}{15}\)
=\(\dfrac{540}{105}-\dfrac{49}{105}\)
=\(\dfrac{491}{105}\)
\(\)a) 4.(-5)2+(-2)3.25
\(=4.5^2+\left(-2\right)^3.25\)
\(=4.25+\left(-8\right).25\)
\(=100+\left(-200\right)\)
\(=-100\)
b) \(15\dfrac{3}{7}-\left(\dfrac{7}{15}+9\dfrac{4}{7}\right)\)
\(=\dfrac{108}{7}-\left(\dfrac{7}{15}+\dfrac{67}{7}\right)\)
\(=\dfrac{108}{7}-\dfrac{1054}{105}\)
\(=\dfrac{566}{105}\)
\(\dfrac{x-7}{y-6}=\dfrac{7}{6}\)
\(\Leftrightarrow6\left(x-7\right)=7\left(y-6\right)\)
\(6x-42=7y-42\)
\(6x=7y\Leftrightarrow x=\dfrac{7}{6}y\)
\(x=-4:\left(7-6\right).7=-28\)
\(y=-28-4=-24\)
b tương tự
Giải:b)
\(\dfrac{x-7}{y-6}=\dfrac{7}{6}\) nên \(6\left(x-7\right)=7\left(y-6\right)\)
Do đó \(6x-42=7y-42\) nên \(6x=7y\)
Suy ra \(6x-6y=y\) hay \(6\left(x-y\right)=y\)
Nên 6.(-4) = y
Vậy y = -24, x = \(\dfrac{7.\left(-24\right)}{6}\)= -28
c)
\(\dfrac{x+3}{y+5}=\dfrac{3}{5}\) nên \(5\left(x+3\right)=3\left(y+5\right)\)
Do đó \(5x+15=3y+15\) nên \(5x=3y\)
Suy ra \(5x+5y=3y+5y\)
\(5\left(x+y\right)=8y\)
\(5.16=8y\)
Nên \(y=\dfrac{5.16}{8}=\dfrac{80}{8}=10\)
Vậy y = 10, x = 16 - 10 =6
Bn nào nhanh nk tick cho