56 - ( x + 2 ) = 22
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\(2\left(x+56\right)\left(x-6\right)=3^{25}:3^{22}\)
\(\Rightarrow2\left(x+56\right)\left(x-6\right)=3^{25-22}\)
\(\Rightarrow2\left(x+56\right)\left(x-6\right)=3^3\)
\(\Rightarrow\left(x+56\right)\left(x-6\right)=\dfrac{27}{2}\)
\(\Rightarrow x^2-6x+56x-336=\dfrac{27}{2}\)
\(\Rightarrow x^2+50x-336=\dfrac{27}{2}\)
\(\Rightarrow x^2+50x+625-961=\dfrac{27}{2}\)
\(\Rightarrow\left(x+25\right)^2=\dfrac{27}{2}+961\)
\(\Rightarrow\left(x+25\right)^2=\dfrac{1949}{2}\)
\(\Rightarrow\left[{}\begin{matrix}x+25=\sqrt{\dfrac{1949}{2}}\\x+25=-\sqrt{\dfrac{1949}{2}}\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=\sqrt{\dfrac{1949}{2}}-25\\x=-\sqrt{\dfrac{1949}{2}}-25\end{matrix}\right.\)
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\(310+\dfrac{1}{5}=\dfrac{1550}{5}+\dfrac{1}{5}=\dfrac{1551}{5}\)
\(\dfrac{6}{7}-\dfrac{1}{2}=\dfrac{12}{14}-\dfrac{7}{14}=\dfrac{5}{14}\)
\(\dfrac{2}{5}\times\dfrac{1}{4}\times\dfrac{2}{3}=\dfrac{4}{60}=\dfrac{1}{15}\)
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a) x + 25 = 53
x = 53 - 25
x = 28
b) x - 56 = 28
x = 28 + 56
x = 84
c) 56 - x = 17
x = 56 - 17
x = 39
d) 22 - x = 16
x = 22 - 16
x = 6
x + 25 = 53
x= 53 - 25
x = 28
x - 56 = 28
x = 28 + 56
x = 84
56 - x = 17
x = 56 - 17
x = 39
22 - x = 16
x = 22 - 16
x = 6
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\(a,\Rightarrow x+2=-40\\ \Rightarrow x=-42\\ b,\Rightarrow6x-7-2x=5\\ \Rightarrow4x=12\Rightarrow x=3\\ c,\Rightarrow68-56-x=-2\\ \Rightarrow12-x=-2\\ \Rightarrow x=14\)
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- 22. (56 - 78) - 78. (22 + 56)=-22.(-22)-78x78
=22^2-78^2
=(22-78).(22+78)
=-56.100
=-5600
Hàng đẳng thức đáng nhớ
\(3.a^2-b^2=\left(a-b\right).\left(a+b\right)\)
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\(56-\left(x+2\right)=22\)
\(x+2=56-22\)
\(x+2=34\)
\(x=34-2\)
\(x=32\)