Ta có: 4,3-2,1=2,2                     6,5-4,3=2,2                           21,9-19,7=2,2

Đây là dãy số cchs đều có khoảng cách là 2,2 đơn vị

Số số hạng là : (21,9-2,1):2,2+1=10 số hạng

Tổng dãy là: (21,9+2,1)x10:2=120

=5.4+6.5+7.6+8.7-4.4-5.5-6.6-7.7

=(5,4 - 4,4)+(6,5-5,5)+(7,6-6.6)+(8,7-7,7)

=1+1+1+1

=4

Dấu chấm là nhân hay phẩy bạn
 

=5.4+6.5+7.6+8.7-4.4-5.5-6.6-7.7

=(5,4 - 4,4)+(6,5-5,5)+(7,6-6.6)+(8,7-7,7)

=1+1+1+1

=4

\(\frac{-16}{11}\)tick na

tick minh nhe

kho..............wa...................troi................thi......................ret.....................ai..............tich...............ung.....................ho....................minh..................voi................ret............wa

4.5+4/11

8.7-4.3

=16

  11

duyệt đi

\(\frac{4.5+4.11}{8.7-4.3}=\frac{16}{11}\)

\(\frac{4.5+4.11}{8.7+4.3}=\frac{4\left(5+11\right)}{4.2.7+4.3}=\frac{4.\left(5+11\right)}{4.14+4.3}=\frac{4.16}{4\left(14+3\right)}=\frac{16}{14+3}=\frac{16}{17}\)

. là dấu nhân hay dấu phẩy vậy bạn

b)[1,1*(-4,3+4,5)]:(-10+10,01)

(1,1*0,2):0,01

=0,22:0,01

=22

c)=(6,7+5,66-3,7+4,34)*(-76,6*1,2+7,66*10*1,2)

=(6,7+5,66-3,7+4,34)*(-76,6*1,2+76,6*1.2)

=(6,7+5,66-3,7+4,34)*[1,2*(-76,6+76,6)]

=(6,7+5,66-3,7+4,34)*(1,2*0)

=(6,7+5,66-3,7+4,34)*0

=0

\(a.\)

\(6,5+1,2+3,5-5,2+6,5-4,8\)

\(=\left(-5,2+1,2\right)+\left(3,5+6,5\right)+\left(6,5-4,8\right)\)

\(=\left(-4\right)+10+1,7\)

\(=6+1,7\)

\(=7,7\)

\(b.\)

\(\left(-4,3.1,1+1,1.4,5\right):\left(-0,5:0,05+10,01\right)\)

\(=\left[1,1.\left(-4,3+4,5\right)\right]:\left(-10+10.01\right)\)

\(=\left[1,1.0,2\right]:\left(0,01\right)\)

\(=0,22:0,01\)

\(=22\)

\(c.\)

\(\left(6,7+5,66-3,7+4,34\right).\left(-76,6.1,2+7,66.12\right)\)

\(=\left(6,7+5,66-3,7+4,34\right).\left[76,6\left(-1,2\right)+7,66.12\right]\)

\(=13.0\)

\(=0\)

ko trung bình

a: \(\dfrac{4\cdot5+4\cdot11}{8\cdot7+4\cdot3}=\dfrac{4\cdot16}{4\left(2\cdot7+3\right)}=\dfrac{16}{17}=\dfrac{11088}{11781}\)

\(\dfrac{-15\cdot8+10\cdot7}{5\cdot6+20\cdot3}=\dfrac{-120+170}{30+60}=\dfrac{50}{90}=\dfrac{5}{9}=\dfrac{6545}{11781}\)

\(\dfrac{2^4\cdot5^2\cdot7}{2^3\cdot5\cdot7^2\cdot11}=2\cdot5\cdot\dfrac{1}{77}=\dfrac{10}{77}=\dfrac{1530}{11781}\)