\(x:33=\dfrac{9}{66}\)
\(x=\dfrac{9}{66}\times33\)
\(x=\dfrac{9}{2}\)
\(\dfrac{4}{5}\times x=\dfrac{10}{11}:\dfrac{3}{4}\)
\(\dfrac{4}{5}\times x=\dfrac{40}{33}\)
\(x=\dfrac{40}{33}:\dfrac{4}{5}\)
\(x=\dfrac{50}{33}\)
#Đạt Đang Bận Thở

\(a,5\frac{1}{4}+3,25-50\%+y=15,25\)

\(\Leftrightarrow5,25+3,25-\frac{50}{100}+y=15,25\)

\(\Leftrightarrow5,25+3,25-0,5+y=15,25\)

\(\Leftrightarrow8+y=15,25\)

\(\Leftrightarrow y=15,25-8=7,25\)

\(b,(y-3):2=2010\)

\(\Leftrightarrow y-3=4020\)

\(\Leftrightarrow y=4023\)

\(c,\frac{7+y}{33}=\frac{9}{11}\)

\(\Leftrightarrow7+y=\frac{9}{11}\cdot33\)

\(\Leftrightarrow7+y=\frac{9}{1}\cdot3\)

\(\Leftrightarrow7+y=27\Leftrightarrow y=20\)

11  =1111

11=1 vì 1=11

11=1111 ban ha

1+2+3+4+5+6+7+8+9+11+22+33+44+55+66+77+88+99=540

1 + 2 + 3 + 4 + 5 + 6 + 7 + 8+ 9 + 11 + 22 + 33 + 44 + 55 + 66 + 77 + 88+ 99

= ( 1 + 2 + 3 + 4+ 5 + 6 + 7 + 8 + 9 ) + ( 11 + 22 + 33 + 44 + 55 +66 +77 + 88 + 99)

= 45                                                 +                   495

=      540

Đặt A=1+2+3+4+5+6+7+8+9

Số  các số hạng của A là 

9-1+1=9(so hang )

tổng A =(9+1).9:2=45

B=11+22+33+44+55+66+77+88+99

=495

vậy tổng 1+2+3+4+5+6+7+8+9+11+22+33+44+55+66+77+88+99=45+495=50

a) \(\dfrac{10^{12}+5^{11}.2^9-5^{13}.2^8}{4.5^5.10^6}\)

\(=\dfrac{2^{12}.5^{12}+5^{11}.2^9-5^{13}.2^8}{2^2.5^5.2^6.5^6}\)

\(=\dfrac{2^{12}.5^{12}+5^{11}.2^9-5^{13}.2^8}{2^8.5^{11}}\)

\(=\dfrac{\left(2^8.5^{11}\right)\left(2^4.5+2-5^2\right)}{2^8.5^{11}}\)

\(=2^4.5+2-5^2\)

\(=57\)

b) \(\dfrac{\left[5\left(x-y\right)^4-3\left(x-y\right)^3+4\left(x-y\right)^2\right]}{\left(y-x\right)^2}\)

\(=\dfrac{\left(x-y\right)^2\left[5\left(x-y\right)^2-3\left(x-y\right)+4\right]}{\left(y-x\right)^2}\)

\(=\dfrac{\left(x^2+y^2-2xy\right)\left[5\left(x-y\right)^2-3\left(x-y\right)+4\right]}{\left(y^2+x^2-2xy\right)}\)

\(=5\left(x-y\right)^2-3\left(x-y\right)+4\)

c) \(\dfrac{\left(x+y\right)^5-2\left(x+y\right)^4+3\left(x+y\right)^3}{-5\left(x+y\right)^3}\)

\(=\dfrac{\left(x+y\right)^3\left[5\left(x+y\right)^2-2\left(x+y\right)+3\right]}{-5\left(x+y\right)^3}\)

\(=\dfrac{5\left(x+y\right)^2-2\left(x+y\right)+3}{-5}\)

Trả lời:

7, 5( x + y )² + 15( x + y )

= 5( x + y )( x + y + 3 )

9, 7x( y - 4 )² - ( 4 - y )³ 

= 7x ( 4 - y )² - ( 4 - y )

= ( 4 - y )² ( 7x - 4 + y )

11, ( x + 1 )( y - 2 ) - ( 2 - y )²

= ( x + 1 )( y - 2 ) - ( y - 2 )²

= ( y - 2 )( x + 1 - y + 2 )

= ( y - 2 )( x - y + 3 )

8, 9x ( x - y ) - 10 ( y - x )² 

= 9x ( x - y ) - 10 ( x - y )²

= ( x - y )[ ( 9x - 10 ( x - y ) ]

= ( x - y )( 9x - 10x + 10y )

= ( x - y )( 10y - x )

10, ( a - b )² - ( a + b )( b - a ) 

= ( b - a )² - ( a + b )( b - a )

= ( b - a )( b - a - a - b )

= - 2a( b - a )

= 2a ( a - b )

12, 2x ( x - 3 ) + y ( x - 3 ) + ( 3 - x )

= 2x ( x - 3 ) + y ( x - 3 ) - ( x - 3 )

= ( x - 3 )( 2x + y - 1 )

hoi vo van

đúng òi vớ va vớ vẩn

Đúng, tui đến đây để cho 1 báo cáo

a) 45

b) 459

c) 495

chúc bạn học tốt~

1+2+3+4+5+6+7+8+9=45

10+20+39+40+50+60+70+80+90=459(Chắc bạn bấm nhầm 30->39)

11+22+33+44+55+66+77+88+99=495

(a)45 (b)459 (c)495

mn. giúp em nha 

\(a.\dfrac{6}{5}=\dfrac{18}{x}\Rightarrow x=\dfrac{18\cdot5}{6}=15\\ \text{Vậy}\text{ }x=15.\)

\(b.\dfrac{3}{4}=\dfrac{-21}{x}\Rightarrow x=\dfrac{-21\cdot4}{3}=28\\ \text{ }\text{ }\text{ }\text{ }\text{Vậy }x=28.\)

\(c.\dfrac{x}{4}=\dfrac{21}{28}\Rightarrow x=\dfrac{21\cdot4}{28}=3\\ \text{Vậy }x=3.\)

\(d.\dfrac{-8}{2x}=\dfrac{3}{-9}\Rightarrow x=\dfrac{-8\cdot\left(-9\right)}{3}:2=12\\ \text{Vậy }x=12.\)

\(e.\dfrac{-4}{11}=\dfrac{x}{22}=\dfrac{40}{z}\\ \Rightarrow x=\dfrac{-4\cdot22}{11}=-8\\ \Rightarrow z=\dfrac{22\cdot40}{-8}=-110\\ \text{Vậy }x=-8;z=-110.\)

\(f.\dfrac{-3}{4}=\dfrac{x}{20}=\dfrac{21}{y}\\ \Rightarrow x=\dfrac{-3\cdot20}{4}=-15\\ \Rightarrow y=\dfrac{21\cdot20}{-15}=-28\\ \text{Vậy }x=-15;y=-28.\)

\(g.\dfrac{-4}{8}=\dfrac{x}{-10}=\dfrac{-7}{y}=\dfrac{z}{-24}\\ \Rightarrow x=\dfrac{-4\cdot\left(-10\right)}{8}=5\\ \Rightarrow y=\dfrac{-7\cdot\left(-10\right)}{5}=14\\ \Rightarrow z=\dfrac{-7\cdot\left(-24\right)}{14}=12\\ \text{Vậy }x=5;y=14;z=12.\)

\(h.\dfrac{x}{4}=\dfrac{9}{x}\\ \Rightarrow x\cdot x=9\cdot4\\ \Rightarrow x\cdot x=36\\ \Rightarrow x\cdot x=6\cdot6\\ \text{Vậy }\text{cả hai }x=6.\)