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Bài 2:
\(a,45+170+25+30\)
\(=\left(45+25\right)+\left(170+30\right)\)
\(=60+200=260\)
Bài 3:
\(a,\left(x-6\right).5=150\)
\(x-6=150:5\)
\(x-6=30\)
\(x=30+6\)
\(x=36\)
\(b,2^5.\left(3x-2\right)=2^3.2^6\)
\(2^5.\left(3x-2\right)=2^{3+6}\)
\(2^5.\left(3x-2\right)=2^9\)
\(3x-2=2^9:2^5\)
\(3x-2=2^4=16\)
\(3x=16+2\)
\(3x=22\)
\(x=22:3\)
\(x\approx7,3\)
\(c,100-7.\left(x-5\right)=51\)
\(7.\left(x-5\right)=100-51\)
\(7.\left(x-5\right)=49\)
\(x-5=49:7\)
\(x-5=7\)
\(x=7+5\)
\(x=12\)
Phần d) bạn thiếu dữ liệu ạ.
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a) 71-(33+x) = 76
71-33-x=76
38-x=76
x = -38
các bài cn lại bn lm tương tự nha!
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Câu 2:
\(a,\Rightarrow8x=56\\ \Rightarrow x=7\\ b,\Rightarrow2\left(x-9\right)=4^2-10=6\\ \Rightarrow x-9=8\\ \Rightarrow x=17\\ c,\Rightarrow x\in BC\left(54,270\right)=B\left(54\right)=\left\{1;2;3;6;9;18;27;54\right\}\\ \text{Mà }20\le x\le30\Rightarrow x=27\)
Câu 3:
\(a,\text{A có }\left(2017-17\right):2+1=1001\left(\text{phần tử}\right)\\ b,P=\left\{2;3;5;7;9\right\}\)
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a ) x = − 91 60 . b ) x = − 8 9 . c ) x = 35 19 . d ) x = 3 7 .
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1a) -54 . 76 + 12 .(-76) + 76.(-34)
= (-54 - 12 - 34).76
= -100 . 76
= -176
b) 37.(63 - 24) - 63.(24 + 37)
= 37 . 63 - 37 . 24 - 63.24 - 63 . 37
= (37.63 - 63.37) - (37 + 63) . 24
= 0 - 100 . 24
= - 2400
2a) x + (-27) = -23 - x
=> x + x = -23 + 27
=> 2x = 4
=> x = 4 : 2
=> x = 2
b) xy + 2x - y = 15
=> x(y + 2) - y = 15
=> x(y + 2) - (y + 2) = 13
=> (x - 1)(y + 2) = 13 = 1 . 13 = 13 . 1
Lập bảng :
x - 1 | 1 | -1 | 13 | -13 |
y + 2 | 13 | -13 | 1 | -1 |
x | 2 | 0 | 14 | -12 |
y | 11 | -15 | -1 | -3 |
Vậy ...
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x + 3 0 : − 45 = − 4 x + 3 0 = − 4 . − 45 x + 3 0 = 18 0 x = 18 0 – 3 0 x = 15 0
\(76-|x|=45\)
\(|x|=31\)
\(\Rightarrow\orbr{\begin{cases}x=31\\x=-31\end{cases}}\)
76 - |x| = 45
|x| = 76 - 45
|x| = 31
=> x ∈ {31;-31}
Vậy x ∈ {31;-31}