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42 - (2x + 32) + 12 = 6.2
42 - (2x + 32) + 12 = 12
42 - (2x + 32 ) = 12 - 12
42 - (2x + 32) = 0
2x + 32 = 42 - 0
2x + 32 = 42
2x = 42 - 32
2x = 10
=> x = 10 : 2
=> x = 5
42 - (2x + 32 )+12:2=6
42 -(2x + 32)+6=6
42-(2x +32)=6-6
42-(2x+32)=0
42-2x=0+32
42-2x=32
2x=42-32
2x=10
x=10:2
x=5
42-(2x+32)+12:2=6
42-(2x+32)+12=6.2=12
42-(2x+32)=12-12
42-(2x+32)=0
2x+32=0+42=42
2x=42-32
2x=10
x=10:2
x=5
42-(2x+32)+12:2=6
42-2x-32+6=6
=> 42-32-2x=0
=> 10-2x=0
=>2x=10=> x=5
cái tính tổng thì theo công thức tính tổng: số đầu+số cuối)x số số hạng:2
số số hạng:(497-2):5+1=100
tổng là: 499x100:2
\(1,42-\left(2x+32\right)+12:2=6\)
\(\Rightarrow42-2x-32=0\)
\(\Rightarrow10-2x=0\)
\(\Rightarrow2x=10\Leftrightarrow x=5\)
\(2,S=2+7+12+17+...+497\)
\(\Rightarrow S=\frac{\left(497+2\right)\left[\left(497-2\right):5+1\right]}{2}\)
\(\Rightarrow S=\frac{499.100}{2}=499.50\)
\(\Rightarrow S=24950\)
a)(x-5):5+22=24
(x-5):5=2
(x-5)=10
x=15
b)42-(2x+32)+12:2=6
42-(2x+32)+6=6
42-(2x+32)=0
(2x+32)=42
2x=10
x=5
\(2,\)
\(a,20-\left[4^2+\left(x-6\right)\right]=90\)
\(\Rightarrow20-16-x+6=90\)
\(\Rightarrow10-x=90\)
\(\Rightarrow x=-80\)
Vậy: \(x=-80\)
\(b,\left(x+3\right)\left(2x-4\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x+3=0\\2x-4=0\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=-3\\x=2\end{matrix}\right.\)
Vậy: \(x\in\left\{-3;2\right\}\)
\(c,1000:\left[30+\left(2^x-6\right)\right]=3^2+4^2\left(x\in N\right)\)
\(\Rightarrow1000:\left(30+2^x-6\right)=25\)
\(\Rightarrow24+2^x=40\)
\(\Rightarrow2^x=16\)
\(\Rightarrow x=4\)
Vậy: \(x=4\)
\(2,\)
\(a,20-\left[42+\left(x-6\right)\right]=90\)
\(\Rightarrow20-42-x+6-90=0\)
\(\Rightarrow x=-106\)
Vậy: \(x=-106\)
\(b,\left(x+3\right)\left(2x-4\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x+3=0\\2x-4=0\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=-3\\x=2\end{matrix}\right.\)
Vậy: \(x\in\left\{-3;2\right\}\)
\(c,1000:\left[30+\left(2x-6\right)\right]=32+42\left(x\in N\right)\)
\(\Rightarrow1000:\left(30+2x-6\right)=74\)
\(\Rightarrow1000:\left(24+2x\right)=74\)
\(\Rightarrow24+2x=\dfrac{500}{37}\)
\(\Rightarrow2x=-\dfrac{388}{37}\)
\(\Rightarrow x=-\dfrac{194}{37}\)
Mà \(x\in N\)
\(\Rightarrow x\in\varnothing\)
Vậy: \(x\in\varnothing\)
a)\(-x+\left(-53\right)=\left(-42\right)-41\Rightarrow-x+\left(-53\right)=\left(-83\right)\Rightarrow x=\left(-83\right)-\left(-53\right)=-30\)b) \(-12-x=-32+19\Rightarrow-12-x=-13\Rightarrow x=12--13=25\)c)\(453+x=-443+-199\Rightarrow453+x=-562\Rightarrow x=-562-453=-1015\)d)(đề trùng b mk ko làm nha)
e) \(32.\left(-2\right)+x=-120-5.\left(-85\right)\Rightarrow-64+x=545\Rightarrow x=545--64=609\)g)
\(-2x+15.\left(-4\right)=21.\left(-8\right)-12\Rightarrow-2x+-60=-180\Rightarrow2x=-120\Rightarrow x=-60\)
\(\Rightarrow42-2x-32+6=6\\ \Rightarrow16-2x=6\\ \Rightarrow2x=10\\ \Rightarrow x=5\)
\(\Rightarrow42-2x-32+6=6\\ \Rightarrow16-2x=6\\ \Rightarrow2x=10\\ \Rightarrow x=5\)