đề 1.
( 76+67 ) - 54 = ??
( 23-17 ) + 47 = ??
đề 2.
( 125+257 ) - 243 = ???
( 147-165 ) + 268 =???
đề 3.
( 1354+2315 ) -1684 = ????
( 6793-4297 ) + 2435 = ????
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a) -34 + 47 + 23 + (-54)
= [-34 + (-54)] + (47 + 23)
= -88 + 70
= -18
b) 76 + (-29) + 93 - (-17)
= 76 + (-29) + 93 + 17
= [76 + (-29)] + (93 + 17)
= 47 + 110
= 157.
Chúc bạn học tốt!
a) 49.(-34)+(-65).49-49 = 49. (-34-65-1)= 49. (-100)= -4900
b) -268-(-47-168)-147 = (-268 + 168) - (147 - 47)= -100 -100=-200
c) (-2)2.(-3)-[(-1)2024+8]:(-3)2 = 4. (-3) - [1 +8]:9 = -12 - 9:9 = -12 - 1 = -13
d) 67-[8+7.32 -24:6+(9-7)3]:15 = 67 - [8 + 7.9 - 4 + 23 ] : 15
= 67 - [8+63-4+8]:15 = 67 - 75:15 = 67 - 5 = 62
1) Tính cụ thể từng bước:
(32-45).(-3)-(-2) mũ 3 -(-7).(-8)
là thế này hả?
\(\left(32-45\right)\left(-3\right)-\left(-2\right)^3-\left(-7\right)\left(-8\right)\)
\(=\left(-13\right)\left(-3\right)+8-56=39+8-56=-9\)
2) Bỏ dấu ngoặc rồi tính:
a) (167+35) + (134-167-35) = 167 + 35 + 134 - 167 - 35 = 134
b) (243-231+57) - (243-231+27) = 243 - 231 +57 -243 +231-27 = 30
c) (89-76) + (76-89-28)= 89 - 76 + 76 - 89 - 28 = -28
d) (243+46-345) - (243-345+54) = 243 + 46 - 345 - 243 + 345 - 54 = 100
* thấy bảo gấp thì làm cho thôi, khỏi tick
a) \(\dfrac{2x+3}{24}=\dfrac{3x-1}{32}\)
\(\Rightarrow32\left(2x+3\right)=24\left(3x-1\right)\)
\(\Rightarrow64x+96=72x-24\)
\(\Rightarrow8x=120\Rightarrow x=15\)
b) \(\dfrac{13x-2}{2x+5}=\dfrac{76}{17}\)
\(\Rightarrow17\left(13x-2\right)=76\left(2x+5\right)\)
\(\Rightarrow221x-34=152x+380\)
\(\Rightarrow69x=414\Rightarrow x=6\)
Bài 1:
1) Ta có: \(\left(-12\right)+6\cdot\left(-3\right)\)
\(=-12-18\)
=-30
2) Ta có: \(\left(36-2020\right)+\left(2019-136\right)-27\)
\(=36-2020+2019-136-27\)
\(=1-100-27\)
\(=-126\)
3) Ta có: \(\left(144-97\right)-\left(244-197\right)\)
\(=144-97-244+197\)
\(=-100+100=0\)
4) Ta có: \(\left(-24\right)\cdot13-24\cdot\left(-3\right)\)
\(=-24\cdot13+24\cdot3\)
\(=24\cdot\left(-13+3\right)\)
\(=24\cdot\left(-10\right)=-240\)
5) Ta có: \(54+55+56+57+58-\left(64+65+66+67+68\right)\)
\(=54+55+56+57+58-64-65-66-67-68\)
\(=\left(54-64\right)+\left(55-65\right)+\left(56-66\right)+\left(57-67\right)+\left(58-68\right)\)
\(=\left(-10\right)+\left(-10\right)+\left(-10\right)+\left(-10\right)+\left(-10\right)\)
=-50
6) Ta có: \(24\cdot\left(16-5\right)-16\cdot\left(24-5\right)\)
\(=24\cdot16-24\cdot5-16\cdot24+16\cdot5\)
\(=-24\cdot5+16\cdot5\)
\(=5\cdot\left(-24+16\right)\)
\(=-5\cdot8=-40\)
7) Ta có: \(47\cdot\left(23+50\right)-23\cdot\left(47+50\right)\)
\(=47\cdot23+47\cdot50-23\cdot47-23\cdot50\)
\(=47\cdot50-23\cdot50\)
\(=50\cdot\left(47-23\right)\)
\(=50\cdot24=1200\)
8) Ta có: \(\left(-31\right)\cdot47+\left(-31\right)\cdot52+\left(-31\right)\)
\(=-31\cdot\left(47+52+1\right)\)
\(=-31\cdot100=-3100\)
Bài 2:
1) Ta có: \(-17-\left(2x-5\right)=-6\)
\(\Leftrightarrow-17-2x+5+6=0\)
\(\Leftrightarrow-2x-6=0\)
\(\Leftrightarrow-2x=6\)
hay x=-3
Vậy: x=-3
2) Ta có: \(10-2\left(4-3x\right)=-4\)
\(\Leftrightarrow10-8+6x+4=0\)
\(\Leftrightarrow6x+6=0\)
\(\Leftrightarrow6x=-6\)
hay x=-1
Vậy: x=-1
3) Ta có: \(-12+3\left(-x+7\right)=-18\)
\(\Leftrightarrow-12-3x+21+18=0\)
\(\Leftrightarrow-3x+27=0\)
\(\Leftrightarrow-3x=-27\)
hay x=9
Vậy: x=9
4) Ta có: \(-45:\left[5\cdot\left(-3-2x\right)\right]=3\)
\(\Leftrightarrow5\cdot\left(-3-2x\right)=-15\)
\(\Leftrightarrow-2x-3=-3\)
\(\Leftrightarrow-2x=0\)
hay x=0
Vậy: x=0
5) Ta có: x(x+3)=0
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x+3=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=-3\end{matrix}\right.\)
Vậy: \(x\in\left\{0;-3\right\}\)
6) Ta có: (x-2)(x+4)=0
\(\Leftrightarrow\left[{}\begin{matrix}x-2=0\\x+4=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=2\\x=-4\end{matrix}\right.\)
Vậy: \(x\in\left\{2;-4\right\}\)
7) Ta có: \(x\left(x+1\right)\left(x-3\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x+1=0\\x-3=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=-1\\x=3\end{matrix}\right.\)
Vậy: \(x\in\left\{0;-1;3\right\}\)
Bài 1:
1) Ta có: (−12)+6⋅(−3)(−12)+6⋅(−3)
=−12−18=−12−18
=-30
2) Ta có: (36−2020)+(2019−136)−27(36−2020)+(2019−136)−27
=36−2020+2019−136−27=36−2020+2019−136−27
=1−100−27=1−100−27
=−126
Tớ chcs cậu học thật giỏi nha !
= 89
= 53
= 139
= 250
= 1985
= 4931
\(\rightarrow\)đáp án đúng \(\leftarrow\)
(76+67)-54=143
(23-17)+47=53