Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
Gọi A là biểu thức ta có:
CÂU1 :A = 1.2+2.3+3.4+......+99.100
3A = 1.2.3 + 2.3.3 + 3.4.3 + … + 99.100.3
3A = 1.2.3 + 2.3.(4 - 1) + 3.4.( 5 - 2) + … + 99.100. (101 - 98)
3A = 1.2.3 + 2.3.4 - 1.2.3 + 3.4.5 - 2.3.4 + … + 99.100.101 - 98.99.100
3A = 99.100.101
A = 99.100.101 : 3
A = 33.100.101
A = 333 300
a, ( - 168 ) + 72 . ( - 168 ) + ( - 168 ) . 27
= ( - 168 ) + ( - 12096 ) + ( - 4536 )
= - 12264 + - 4536
= - 16800
b, 22 . ( - 3 ) - ( 110 + 8 ) : ( - 3 )2
= 4 . ( - 3 ) - ( 1 + 8 ) : 9
= ( - 12 ) - 9 : 9
= ( - 12 ) - 1
= - 13
c, ( - 1075 ) - ( 29 - 1075 )
= ( - 1075 ) - ( - 1046 )
= - 29
d, ( - 9 ) + ( - 11 ) + 21 + ( - 1 )
= - 20 + 21 + ( - 1 )
= 1 + - 1
= 0
e, 30 + 12 + ( - 20 ) + ( - 12 ) - ( 30 - 20 ) + ( 12 - 12 )
= 42 + ( - 20 ) + ( - 12 ) - 10 + 0
= 22 + ( - 12 ) - 10 + 0
= 10 - 10 + 0
= 0 + 0
= 0
g, ( 13 - 135 + 49 ) - ( 13 + 49 )
= [( - 122 ) + 49 ] - 62
= ( - 73 ) - 62
= - 135
h, 35 - { 12 - [ ( - 14 ) + ( - 2 ) } ]
= 35 - { 12 - ( - 16 ) }
= 35 - 28
= 7
Bài 2:
a. x - 35 = ( - 12 ) - 3
x - 35 = - 15
x = - 15 + 35
x = 20
b, \(\frac{1}{4}\)+ \(\frac{1}{3}\): 3x = - 5
\(\frac{3}{12}+\frac{4}{12}\): 3x = - 5
\(\frac{7}{12}\): 3x = - 5
3x = \(\frac{7}{12}\): - 5
3x = \(\frac{-7}{60}\)
x = \(\frac{-7}{60}\): 3
x = \(\frac{-7}{180}\)
c,2x-1 = 8
2x-1 = 24
x = 4 + 1
x = 5
k,(x + 1) + (x + 2) + (x + 3) + .... + (x + 100) = 5750
=> 100x + (1 + 2 + 3 + ... + 100) = 5750
=> 100x + 5050 = 5750
=> 100x = 5750 - 5050
=> 100x = 700
=> x = 700 : 100
=> x = 7
i,92.4 - 27 = (x + 350) : x + 315
=> 1 + 350 : x + 315 = 341
=> 350 : x = 341 - 316 = 25
-> x = 350: 25 = 14
a)35-(12-(-14+(-2)))
=35-(12-(-12))
=35-(12+12)
=35-24
=11
b)49-(-54)-23
=49+54-23
=103-23
=80
c)5871:(928-((-82)+247))×5)
=5871:(928-165×5)
=5871:(928-825)
=5871:103
=57
1, Tính :
a, \(8.4^5-3.9.12+28\div4.2^0\)
\(=8192-27.12+7.1\)
\(=8192-324+7\)
\(=7868+7\)
\(=7875\)
b, \(210+86.2^3\div2-19.2^3\)
\(=210+86.8\div2-19.8\)
\(=210+688\div2-19.8\)
\(=210+344-152\)
\(=554-152=402\)
c, \(54.23+11^2-152\)
\(=54.23+121-152\)
\(=1242+121-152\)
\(=1363-152=1211\)
2, Tính giá trị của biểu thức :
a, \(311\div\left\{210+\left[53+\left(37-25\right).2^2\right]\right\}\)
\(=311\div\left\{210+\left[53+12.4\right]\right\}\)
\(=311\div\left\{210+\left[53+48\right]\right\}\)
\(=311\div\left\{210+101\right\}\)
\(=311\div311=1\)
Vậy giá trị biểu thức trên bằng 1
b, \(\left\{\left[200+\left(50-30\right)^2\right]-456\right\}\div12\)
\(=\left\{\left[200+20^2\right]-456\right\}\div12\)
\(=\left\{\left[200+400\right]-456\right\}\div12\)
\(=\left\{600-456\right\}\div12\)
\(=144\div12=12\)
Vậy giá trị biểu thức trên bằng 12
b) \(3.2^{x+1}=12\)
\(2^{x+1}=12:3\)
\(2^{x+1}=4\)
\(2^{x+1}=2^2\)
\(x+1=2\)
\(x=2-1\)
\(x=1\)
Vậy \(x=1\)
c) \(2^{x-1}=2^3+2^4-2^3\)
\(2^{x-1}=8+16-8\)
\(2^{x-1}=16\)
\(2^{x-1}=2^4\)
\(x-1=4\)
\(x=5\)
Vậy \(x=5\)
d) \(x^{50}=x\)
\(x^{50}-x=0\)
\(\Rightarrow x\in\left\{0;1\right\}\)
Vậy \(x\in\left\{0;1\right\}\)
\(b.3.2^{x+1}=12\\ \Rightarrow2^{x+1}=4\\ \Rightarrow2^{x+1}=2^2\\ \Rightarrow x=1\\ \)
c) \(2^{x-1}=2^3-2^3+2^4\\ \Rightarrow2^{x-1}=0+16\\ \Rightarrow2^{x-1}=16\\ \Rightarrow2^{x-1}=2^4\\ \Rightarrow x-1=4\\ \Rightarrow x=5\)
d) \(x^{50}=x\\ \Rightarrow x=0;1\)
e) \(2\left(2x-1\right)^4=32\\ \Rightarrow\left(2x-1\right)^4=16\\ \Rightarrow\left(2x-1\right)^4=2^4\\ \Rightarrow2x-1=2\\ \Rightarrow2x=3\\ \Rightarrow x=\frac{3}{2}\)
g) Bí