Question

1.Tính nhanh:

a) 35.23+35.41+64.65

b)29.87-29.23+64.71

c)48.19+48.115+134.52

d)27.121-87.27+73.34

e)125.98-125.46-52.25

f)136.23+136.17-40.36

g)17.93+116.83+17.23

h)19.27+47.81+19.20

i)87.23+13.93+70.87

2.Tìm X:

a.[(6.x-39):7].4=12

b.(x:3-4).5=15

c.128-3.(x+4)=23

d.\(\left(3.x-3^4\right).7^3=2.7^4\)

x-[42+(-28)]=-8

g) x-7=-5

h) 15-5.(x+4)=-12-3

i) (7-x)-(25+7)=-25

k) 0:x=0

l) \(4^x=64\)

m) \(9^{x-1}=9\)

n) \(2^x:2^5=1\)

Answer 1

1)

a) 35.23 + 35.41 + 64.65 = 35(23+41) + 64.65 = 35 . 65 + 64.65 =65. 99 = 65(100 - 1 ) = 6500 - 65 = 6435

b) 29.87 - 29.23 + 64.71 = 29(87-23) + 64.71 = 29.64 + 64.71 = 64(71+29) = 64.100= 6400

c) 48.19 + 48.115 + 134.52 = 48(19+115) + 134.52 = 48 . 134+134.52=134(52+48)=134.100=13400

d) 27.121 - 87.27 + 73.34 = 27(121-87) +73 .34 = 27 .34 + 73.34 = 34(73+27)=34.100=3400

e) 125.98-125.46-52.25 = 125(98-46) -52.25 = 125 . 52 - 52.25 =52(125-25) =52.100=5200

f)136.23 + 136.17 - 40.36 = 136(23+17) - 40.36 = 136.40 -40.36 = (136-36)40 = 100.40=4000

g) 17.93 + 116.83 + 17.23 = 17(93+23) + 116.83 = 17.116 + 116.83 =116(83+17) = 116.100=11600

h)19.27 +47.81 + 19.20 = 19(27+20) + 47.81 = 19. 47 + 47.81 = 47(81+19)=47.100 = 4700

i) 87.23 + 13.93 + 70.87 = 87(23+70) + 13.93 = 87 .93 + 13.93 = 93(87+13)=93.100=9300

2)Tìm x

a) [(6x-39):37].4 = 12 

(6x - 39) : 37 = 12 : 4 = 3

x =(3.37 + 39): 6 = 25

b) ( x : 3 - 4 ) .5=15

x : 3 -4 = 3

x = (3+4).3 = 21

c) 128 - 3(x+4) =23

3x + 12 = 128 -23 = 105

x = (105-12):3 = 31

d) (3x - 3⁴).7³=2.7⁴

3x - 81 = 2.7⁴:7³=2.7=14

x =(81 + 14 ) : 3= \(31\frac{2}{3}\)

e) x - [42 + (-28) ] = -8 

x - 14 = -8 

x- 14 + 14 = -8 + 14 

x = 6

Answer 2

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