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

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

\(=16,5+1,2-10\)

\(=17,7-10=7,7\)

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

\(=1,1\left(-4,3+4,5\right):\left(-10+10,01\right)\)

\(=1,1.0,2:0,01\)

\(=1,1.20=22\)

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

\(=\left[\left(5,66+4,34\right)+\left(6,7-3,7\right)\right]\left[7,66.\left(-10\right).1,2+7,66.12\right]\)

\(=\left(10+3\right).\left[7,66\left(-12\right)+7,66.12\right]\)

\(=13.0=0\)

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

=10-10+7,7=7,7

\(\text{(-4,3.1,1+1,1.4,5): (-0,5:0,05+10,01)}=\dfrac{1,1.\left(-4,3+4,5\right)}{-10+10,01}=\dfrac{0,22}{0,01}=22\)

\(\text{(6,7+5,66-3,7+4,34). (-76,6.1,2+7,66.12)}\)

=(6,7+5,66-3,7+4,34)(-76,6.1,2+76,6.1,2)=0

bài 2)

a)|12,1x+12,1.0,1|=12,1

<=> |12,1(x+0,1)|=12,1

<=>\(\left[\begin{array}{nghiempt}12,1\left(x+0,1\right)=12,1\\12,1\left(x+0,1\right)=-12,1\end{array}\right.\)

<=> \(\left[\begin{array}{nghiempt}x=0,9\\x=-1,1\end{array}\right.\)

b) |0,2x-3,1|+|0,2+3,1|=0

<=>|0,2x-3,1|+3,3=0

ta có |A|>=0

=> pt trên vô nghiệm

bài 1) a) 6,5+1,2+3,5-5,2+6,5-4,8

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

=15,5-8,8=24,6

tt nha bạn

1. Tính nhanh

a) 6,5+1,2+3,5-5,2+6,5-4,8

= 6,5+1,5+3,5+6,5-5,2-4,8

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

= 16,5+1,2-10

= 17,7-10

=7,7

b) (-4,3.1,1+1,1.4,5):(-0,5:0,05+10,01)

=  {1,1.[(-4,3)+4,5)} : [(-10)+10,01]

= ( 1,1.0.2 ) : 0,01

= 1,1 : 5 . 100

= 1,1 . 20

= 22

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

= [(5,66+4,34)+(6,7-3,7)]. [ 7,66. (-10).1,2+7,66.12)]

= ( 10+ 3) . [7,66.(-12)+7,66.12]

= 13. { 7,66. [ (-12)+12]}

= 13. (7,66 . 0)

= 13

2. So sánh x và y

x= (42-4,2.10+76:7,6):(0,01.0,1)

y=(689,7+0,3):(7,4:0,2-2,2-1,5)

                                                                                                  Giải

Ta có: x= (42-4,2.10+76:7,6):(0,01.0,1)

=> x= ( 42-42 + 10 ) : 0,001

=> x= 10 : 0,001

=> x= 10.1000

=> x= 10000         (1)

Lại có: y=(689,7+0,3):(7,4:0,2-2,2-1,5)

=> y= 690: ( 37-2,2-1,5)

=> y= 690 : 33,3           (2)

Từ (1) và (2) => x > y

1+1

2+2

3+3

4+4

a) 7,7 (7\(\frac{7}{10}\))

b) 0,484(\(\frac{968}{2001}\))

c) ko có giá trị tương ứng

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

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

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

\(=16,5+1,2-10\)

\(=17,7-10\)

\(=7,7.\)

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

\(=\left\{1,1.\left[\left(-4,3\right)+4,5\right]\right\}:\left[\left(-10\right)+10,01\right]\)

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

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

\(=22.\)

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

\(=\left[\left(5,66+4,34\right)+\left(6,7-3,7\right)\right].\left[7,66.\left(-10\right).1,2+7,66.12\right]\)

\(=\left[10+3\right].\left[7,66.\left(-12\right)+7,66.12\right]\)

\(=13.\left\{7,66.\left[\left(-12\right)+12\right]\right\}\)

\(=13.0\)

\(=0.\)

Chúc bạn học tốt!

( 6,7 + 5,66 - 3.7 +4,34 ).( -76,6 .1,2 +7,66 .12 )

= [( 6,7 -3,7 ) + ( 5,66 + 4,34 )].[ -7,66 . 12 + 7,66 . 12 )

= ( 3 + 10 ).[ 12 . ( -7,66 + 7,66 )]

= 13 . 0

= 0

\(\left(6,7-5,66-3,7+4,34\right)\cdot\left(-76,6\cdot1,2+7,66\cdot12\right)\)

\(=\left[\left(6,7-3,7\right)+\left(5,66+4,34\right)\right]\left[-7,66\cdot12+7,66\cdot12\right]=\left(3\cdot10\right)\cdot0=0\)

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

= (6,7 + 5,66 - 3,7 + 4,34) . [7,66 . (12 - 12)]

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

= 0

bo chiu

=(6,7+5,66 -3,7+4,34).(-7,66.12+7,66.12)

=(6,7+5,66 -3,7+4,34).[(-7.66+7.66).12]

=(6,7+5,66 -3,7+4,34).(0.12)

=(6,7+5,66 -3,7+4,34).0

=0 

Ta có:

-76,6 .1,2 + 7,66 . 12 

= -7,66 .10 .1,2 + 7,66 . 12

= -7,66 . 12 + 7,66 .12

= 12 . ( -7,66 + 7,66 )

= 12 . 0

= 0

\(\Rightarrow\left(6,7+5,66-3,7+4,34\right).\left(-76,6.1,2+7,66.12\right)=\left(6,7+5,66-3,7+4,34\right).0=0\)

bấm máy tính là nhanh nhất