a) 465 + [ 57 + ( -465) + ( -38 ) ]

= 465 + 57 + ( -465) + ( -38 )

=465 + ( - 465) + 57 + ( -38 )

= 0 + 19

= 19

b) Theo đầu đề bài ta có tổng:

(-15 ) + (-14) + (-13) + ... + 13 + 14 + 15

= [( -15 ) + 15] + [( -14) + 14 ]+ .... + [(-1) + 1] + 0

= 0

a) 465 + [57 + ( -465) + ( -38)]

= 465 + 57 + ( - 465 ) + ( - 38 )

= 465 + ( - 465 ) + 57 + ( - 38 )

= 0 + 19

= 19

b) Theo đề ta có tổng :

( - 15 ) + ( - 14 ) + ( - 13 ) + ... + 13 + 14 + 15

= [ ( - 15 ) + 15 ] + [ ( - 14 ) + 14 ] + ... + [ ( - 1 ) + 1 ] + 0

= 0

A=\(\frac{3}{5}\): \(\frac{4}{5}\) + \(\frac{3}{7}\):\(\frac{4}{7}\)+ \(\frac{3}{13}\): \(\frac{4}{13}\)+\(\frac{3}{295}\): \(\frac{4}{295}\)

A= \(\frac{3}{4}\)+ 3/4 + 3/4 + 3/4

A=3/4 . 4 = 3

Ta có: \(\frac{3}{5}+\frac{3}{7}+\frac{3}{13}+\frac{3}{295}=3.\left(1+\frac{1}{5}+\frac{1}{7}+\frac{1}{13}+\frac{1}{295}\right)\)

\(\frac{4}{5}+\frac{4}{7}+\frac{4}{13}+\frac{4}{295}=4.\left(1+\frac{1}{5}+\frac{1}{7}+\frac{1}{13}+\frac{1}{295}\right)\)

\(\Rightarrow\frac{\frac{3}{5}+\frac{3}{7}+\frac{3}{13}+\frac{3}{295}}{\frac{4}{5}+\frac{4}{7}+\frac{4}{13}+\frac{4}{295}}=\frac{3.\left(1+\frac{1}{5}+\frac{1}{7}+\frac{1}{13}+\frac{1}{295}\right)}{4.\left(1+\frac{1}{5}+\frac{1}{7}+\frac{1}{13}+\frac{1}{295}\right)}=\frac{3}{4}\)

465+[58+(465+(-38)]

=465+[58+427]

=465+485

=950

=465+[58+465+(-38)]

=465+58+465+(-38)

=(465+465)+[58+(-38)]

=930+20

=950

các bạn cho mk vài li-ke cho tròn 600 với 

=295-(31-4.5)²

=295-(31-20)²

=295-11²

=295-121

=174

.

=295-(31-20)²

=295-11²=295-121=174

1. 

a/ 70-5.(x-3) = 5.32

=>70-5.(x-3) = 160

=> 5.(x-3)     = -90

=> x-3          = -18

=> x             = -15

Vậy x = -15.

b/ 2x-3 = 16

=> 2x   = 16 + 3

=> 2x   = 19

=> x     = 9,5

Vậy x = 9,5.

2. Thực hiện phép tính:

a/ 248 + (-12) + 2064 + (-236)

= 236 + 2064 + (-236)

= (236 + (-236)) + 2064

= 0 + 2064

= 2064

b/ /-23/ + (-15) + (-34)

= 23 + (-15) + (-34)

= 8 + (-34)

= -26

c/ 456 + (56 + (-456) + (-38))

= (456 + (-456)) + (56 + (-38))

= 0 + 18

=18

Tiện thể, cho mk hỏi cậu dùng GTTĐ và ngoăc vuông kiểu gì zợ? ^.^

\(295-\left(31-4.5\right)^2=295-\left(31-20\right)^2=295-\left(11\right)^2=295-121=174\)

295 - ( 31 - 2 ² . 5 ) ²

= 295 - ( 31 - 20 ) ²

= 295 - 11 ²

= 295 - 121

= 174

465 +[58 + (-465) + (-38)] = [465 + (-465)] + [58 + (-38)] = 0 + 20 = 20

=465-38-465+12+420

=(465-465)-38+12+420

= -26+420

=394

465 + [(-38) + (-465)] - [12 - (-42)]

= 465 + ( - 38) + ( -465) – 12 – 42      

= [ 465 + (- 465) ] – ( 12 + 42 )       

= 0 – 54 = 0 + ( -54 ) = -54