a)\(A=\left\{\left(0,1+0,9\right)+\left(0,2+0,8\right)+\left(0,3+0,7\right)+\left(0,4+0,6\right)+0,5\right\}\)

\(A=4.\left(1\right)+0,5=4,5\)

\(B=\left\{\left(1,01+1,09\right)+...\left(1,04+1,06\right)+1,05\right\}+1,1\)

\(B=4.\left(2,1\right)+1,05+1,1=8,4++1,05+1,1=10,46\)

A+B=4,5+10,46=14,96

a)4,5

b)14,96

ai tk mk

mk tk lại

mk hứa

yên tâm

thank nhiều

b) 120 - 0,5x40x5x0,2x20x0,25 - 20

= 120 - (0,5 x 0,2)x ( 40 x 0,25)x ( 20 x 5) - 20

= 120 - 0,1 x 10 x 100 - 20

= 120 - 100 -20

=0

\(=\frac{120-0,5\cdot40\cdot5\cdot0,2\cdot20\cdot0,25-20}{1+5+9+.....+33+37}\)

\(=\frac{120-20-\left(0,5\cdot20\right)\cdot\left(5\cdot0,2\right)\cdot\left(40\cdot0,25\right)}{1+5+9+.....+33+37}\)

\(=\frac{100-10\cdot1\cdot10}{1+5+9+.....+33+37}\)

\(=\frac{100-100}{1+5+9+.....+33+37}\)

\(=\frac{0}{1+5+9+.....+33+37}\)

\(=0\)

Ta có:\(120-0,5\times40\times5\times0,2\times20\times0,25-20=120-100-20=0\)

\(\Rightarrow\frac{120-0,5\times40\times5\times0,2\times20\times0,25}{1+5+.......+37}=\frac{0}{1+5+9+.....+37}=0\)

Vậy...........

thanks

leu leu

\(27\cdot25\cdot\left(3+1\right)-230=27\cdot25\cdot4-230\)

có thể trình bày rõ ràng ra ko

\(\frac{25\times4-0,5\times40\times5\times0,2\times20\times0,25}{1+2+4+8+...+128+256}\)

\(=\frac{100-\left(20\times5\right)\times\left(0,5\times0,2\times0,25\times40\right)}{1+2+4+8+...+128+256}\)

\(=\frac{100-100\times\left(\frac{1}{40}\times40\right)}{1+2+4+8+...+128+256}\)

\(=\frac{100\times\left(1-1\right)}{1+2+4+8+...+128+256}\)

\(=0\)

\(\frac{25\times4-0,5\times40\times5\times0,2\times20\times0,25}{1+2+4+8+...128+256}\)

\(=\frac{100-\left(0,5\times20\right)\times\left(40\times0,25\right)\times\left(5\times0,2\right)}{1+2+4+8+...+128+256}\)

\(=\frac{100-10\times10\times1}{1+2+4+8+...+128+256}\)

\(=\frac{100-100}{1+2+4+8+...+128+256}\)

\(=\frac{0}{1+2+4+8+...+128+256}=0\)

\(\frac{25\cdot4-0.5\cdot40\cdot5\cdot0.2\cdot20\cdot0.25}{1+2+...+128+256}\)

\(=\frac{100-0.25\cdot20\cdot5}{256\cdot2-1}\)

\(=\frac{100-0.25\cdot100}{512-1}\)

\(=\frac{100-25}{511}\)

\(=\frac{75}{511}\)

120 - 0,5 x 40 x 5 x 0,2 x 20 x 0,25 - 20

= ( 120 - 20 ) - [ ( 0,5 x 20 ) x ( 40 x 0,25 ) x ( 0,2 x 5 ) ]

=       100      - [      10        x       10         x     1         ]

=       100      -              100

= 0

\(120-0,5\times40\times5\times0,2\times20\times0,25-20\)

\(=120-\left(0,5\times20\right)\times\left(40\times0,25\right)\times\left(5\times20\right)-20\)

\(=120-10\times10\times100-20\)

\(=120-10000-20\)

\(=-9900\)

kết quả là 80 mới đúng

120-0,5x40x5x0,2x20x0,25-20

= 120-(0,5x20)x(40x0,25)x0,2-20

=120-10x10x0,2-20

=120-100x0,2-20

=120-20-20

=80

25*4-0,5*40*5*0,2*20*0,25 = 0