1: Tính

a: 27+ 55+ (-17) + (-55)

= (27-17) + (55-55)

= 10 + 0

= 10

b: (-92)+ (-251)+ (-8)+ 25

= -(92+8) - (251 - 25)

= -100 - 226

= -326

c: (235- 47) + (175- 53)

= 235 - 47 + 175 - 53

= (235+175) - (47+53)

= 410 - 100

= 310

d: (756- 217)- (183- 44)

= 756 - 217 - 183 + 44

= (756+44) - (217+183)

= 800 - 400

= 400

2: Tìm x, biết

\(\text{x. (x+ 3)= 0}\)

\(\Rightarrow\orbr{\begin{cases}x=0\\x+3=0\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=0\\x=-3\end{cases}}\)

vậy______

\(\text{(x-2). (5- x) = 0}\)

\(\Rightarrow\orbr{\begin{cases}x-2=0\\5-x=0\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=2\\x=5\end{cases}}\)

vậy________

(x- 3). (2x +1) = 7

=> x-3 và 2x + 1 thuộc Ư(7)

ta có bảng sau :

vậy x thuộc {4;3;2;-3;10;0;-4;-1}

a: 27+ 55+ (-17) + (-55)

=27 + 55 -17 - 55

=10

b: (-92)+ (-251)+ (-8)+ 25

= -92 - 251 - 8 + 25

=-326

c: (235- 47) + (175- 53)

=188 + 122

=310

d: (756- 217)- (183- 44)

=539 - 139

=400

Bài 1:

a) 27 + 55 + (-17) + (-55)

= (27 - 17) + (55 - 55)

= 10 + 0

= 10

b) (-92) + (-251) + (-8) + 25

= (-92 - 8) - (251 - 25)

= (-100) - 226

= -326

c) (235 - 47) + (175 - 53)

= 235 - 47 + 175 - 53

= (235 + 175) - (47 + 53)

= 410 - 100

= 310

d) (756 - 217) - (183 - 44)

= 756 - 217 - 183 + 44

= (756 + 44) - (217 + 183)

= 800 - 400

= 400

Ai giúp tui với =)))))

283-286-83+86-55

= (283-83)+(286+55)-86

= 200+ 231-86=345

C) 38x(27-44) -27 x (38-44)

= 38x27-38x44-27x38-27x44

=(38x27-27x38) + (38x44-27x44)

=0+484

=484

\(283-286-83+86-55\)

\(=\left(283-83\right)+\left(-286+86\right)+\left(-55\right)\)

\(=200+\left(-200\right)+\left(-55\right)\)

\(=\left(-55\right)\)

c) \(38\times\left(27-44\right)-27\times\left(38-44\right)\)

\(=38\times27-38\times44-27\times38+27\times44\)

\(=\left(38\times27-27\times38\right)+\left(27\times44-38\times44\right)\)

\(=0+44\times\left(27-38\right)\)

\(=44\times\left(27-38\right)\)

\(=44\times\left(-11\right)\)

\(=\left(-484\right)\)

Chúc bạn học tốt

88+44=132

55+55=110

=132

=110

88 + 44 = 132

55 + 55 = 110

\(e,112-45+5x=87\)

\(67+5x=87\)

\(5x=20\)

\(x=4\)

\(f,6^2+64:\left(x-1\right)=52\)

\(36+64:\left(x+1\right)=52\)

\(64:\left(x+1\right)=16\)

\(x+1=4\)

\(x=3\)

\(g,\left(55-x\right)\left(2x-44\right)=0\)

\(\Rightarrow\hept{\begin{cases}55-x=0\\2x-44=0\end{cases}}\)

\(\Rightarrow\hept{\begin{cases}x=55\\x=22\end{cases}}\)

Vậy ....

\(h,x^2+4=13\)

\(x^2=9\)

\(x^2=\pm3^2\)

\(\Rightarrow x=\pm3\)

\(i,2\left(x+1\right)^3=16\)

\(\left(x+1\right)^3=8\)

\(\left(x+1\right)^3=2^3\)

\(\Rightarrow x+1=2\)

\(x=1\)

\(g,150-5\left(x-2\right)^2=25\)

\(5\left(x-2\right)^2=125\)

\(\left(x-2\right)^2=25\)

\(\left(x-2\right)^2=\pm5^2\)

\(\Rightarrow\hept{\begin{cases}x-2=5\\x-2=\left(-5\right)\end{cases}\Rightarrow\hept{\begin{cases}x=7\\x=\left(-3\right)\end{cases}}}\)

Vậy .... 

hoac sai vi tui moi lop 3

honh phai

11nhan11

22nhan22

33nhan33

co hong phai nhu the

* la dau nhan

: la dau cach giua cac phep thinh

x = \(\frac{-88}{9}\).

y = \(\frac{-44}{3}\).

z = \(\frac{220}{9}\).

x = -88/9

y = -44/3

z = 220/9

k tui nha

x = -88/9

y = -44/3

z = 220/9

-Cái này áp dụng hằng đẳng thức số 3 á.

\(\left(2x-5\right)^2-\left(x+2\right)^2=0\)

\(\Leftrightarrow\left(2x-5+x+2\right)\left(2x-5-x-2\right)=0\)

\(\Leftrightarrow\left(3x-3\right)\left(x-7\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}3x-3=0\\x-7=0\end{matrix}\right.\) \(\Leftrightarrow\left[{}\begin{matrix}x=1\\x=7\end{matrix}\right.\)

Vậy...

Bài eassy

\(\left(2x-5\right)^2-\left(x+2\right)^2\)

\(\Leftrightarrow\left(2x-5-x-2\right)\left(2x-5+x+2\right)=0\)

\(\Leftrightarrow\left(x-7\right)\left(3x-3\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x-7=0\\3x-3=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=7\\x=1\end{matrix}\right.\)

Vậy.....................

Một cách khác dài hơn -.-

\(\left(2x-5\right)^2-\left(x+2\right)^2=0\)

\(\Leftrightarrow4x^2-20x+25-x^2-4x-4=0\)

\(\Leftrightarrow3x^2-24x+21=0\)

\(\Leftrightarrow\left(3x^2-21x\right)-\left(3x-21\right)=0\)

\(\Leftrightarrow x\left(3x-21\right)-\left(3x-21\right)=0\)

\(\Leftrightarrow\left(x-1\right)\left(3x-21\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x-1=0\\3x-21=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=1\\x=7\end{matrix}\right.\)

Vậy...........

45+56+55+44=200

mk hok lop 6 cung tuoi thi tk nha

45 + 56 + 55 + 44

=> 45 + 55 + 56 + 44

=>    100     +    100

=>            200

45 + 56 + 55 + 44 

= 101 + 55 + 44

= 156 + 44

= 200