Bài 3: 

b: \(x\in\left\{3;-3\right\}\)

c: =547x100=54700

d: =-76x10=-760

b: \(x=720\)

a)12/23

   18/39

    24/52

   30/65 

   36/78

   42/91

b) 45/-21

    75/-35

Bài 1 : Tính nhanh

a) 2016 + [ 520 + (-2016) ]

= 2016 + 520 + (-2016)

= [2016 + (-2016)] + 520

= 0 + 520 = 520

b) [(-851) + 5924] + [(-5924) + 851]

= [(-851) + 851] + [(-5924) + 5924]

= 0 + 0 = 0

c) 921 + [ 97 + (-921) + (-47)]

= 921 + 97 + (-921) + (-47)

= 921 + (-921) + 97 + (-47)

= 0 + 50 = 50

d) 2014 + 2015 + (-2016) + (-2017) 

= 2014 + (-2016) + 2015 + (-2017)

= 2 + 2 = 4

Bài 2 : Tính tổng các số nguyên x thỏa mãn : 

a) Để -7 < x < 6 thì x = { -6 , -5 , -4 , -3 , -2 , -1 , 0 ,1 ,2,3,4,5}

Tổng các số nguyên x thỏa mãn là : 

    (-6) + [(-5) + 5] + [(-4) +4] + [(-3) + 3] + [(-2) + 2) + [(-1) + 1] + 0

= (-6) + 0 + 0 + 0 + 0 + 0 + 0

= -6

Bài 3: 

b: \(\Leftrightarrow\left(x-3\right)\left(x+3\right)=0\)

hay \(x\in\left\{3;-3\right\}\)

=415-{-215-[-115-315+2016]}

=415-{-215-115+315-2016}

=415-215+115-315+2016

=5+2016

=2021

Bài 3:

\(a,\left(5x-2\right)+\left(-3x+1\right)=\left(-42\right)-\left(-91\right)\\ \Rightarrow5x-2+\left(-3x\right)+1=50\\ \Rightarrow2x-1=49\\ \Rightarrow2x=50\\ \Rightarrow x=25\\ b,\left(3-x\right)\left(9+3x\right)=0\\ \Rightarrow\left[{}\begin{matrix}3-x=0\\9+3x=0\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=3\\3x=-9\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=3\\x=-3\end{matrix}\right.\)

\(c,5x^2-\left(-6\right)=\left(-33\right)-\left(-44\right)\\ \Rightarrow5x^2+6=11\\ \Rightarrow5x^2=5\\ \Rightarrow x^2=1\\ \Rightarrow\left[{}\begin{matrix}x=-1\\x=1\end{matrix}\right.\)

\(d,2\left(2x-4\right)^2-77=-45\\ \Rightarrow2\left(2x-4\right)^2=32\\ \Rightarrow\left(2x-4\right)^2=16\\ \Rightarrow\left[{}\begin{matrix}2x-4=-4\\2x-4=4\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}2x=0\\2x=8\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=0\\x=4\end{matrix}\right.\)

bài 3

c] 5x mũ 2 -[-6] =[-33] - [-44]

cho xin một like đi

c: 

hay 

d: 

hay 

a: 

hay 

b: \(\Leftrightarrow n+1\in\left\{1;-1;2;-2;4;-4\right\}\)

hay \(n\in\left\{0;-2;1;-3;3;-5\right\}\)

c: \(\Leftrightarrow n+2\in\left\{1;-1;5;-5\right\}\)

hay \(n\in\left\{-1;-3;3;-7\right\}\)

d: \(\Leftrightarrow n+2\in\left\{1;-1;2;-2;4;-4\right\}\)

hay \(n\in\left\{-1;-3;0;-4;2;-6\right\}\)

a: \(\Leftrightarrow n-1\in\left\{1;-1;5;-5\right\}\)

hay \(n\in\left\{2;0;6;-4\right\}\)