1.Tính hợp lí a,-|-8| + (-2) mũ 2 – (-1) mũ 2021 b,(-45) . 165 + 45 . 65 c,35 . (25 + 147) – 25 . (35 + 147 ) 2.Tìm x a,( x – 4 ) mũ 3 – 9 = -17 b,3 –

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1. Đáp án:

    $1)
   a)
   -5\\
   b)
   -4500\\
   c)
   1470\\
   2)
   a)
   x=2\\
   b)
   {\left[\begin{aligned}x=2\\x=-8\end{aligned}\right.}\\
   c)
    {\left[\begin{aligned}x=8\\x=\frac{-18}{3}\end{aligned}\right.}\\$

   Giải thích các bước giải:

    $1)
   a)
   -\left | -8 \right |+(-2)^2-(-1)^{2021}\\
   =-8+4-1=-5\\
   b)
   (-45).165+45.65\\
   =45.(-165+65)=45.(-100)=-4500\\
   c)
   35.(25+147)-25.(35+147)\\
   =35.25+35.147-25.35-25.147\\
   =(35.25-25.35)+(35.147-25.147)\\
   =0+147.(35-25)=147.10=1470\\
   2)
   a)
   (x-4)^3-9=-17\\
   \Leftrightarrow (x-4)^3=-17+9=-8\\
   \Leftrightarrow x-4=-2\\
   \Leftrightarrow x=-2+4=2\\
   b)
   3-\left | x+3 \right |=-2\\
   \Leftrightarrow \left | x+3 \right |=3+2=5\\
   \Leftrightarrow {\left[\begin{aligned}x+3=5\\x+3=-5\end{aligned}\right.}\\
   \Leftrightarrow {\left[\begin{aligned}x=2\\x=-8\end{aligned}\right.}\\
   c)
   (-8+x)(3x+18)=0\\
   \Leftrightarrow {\left[\begin{aligned}-8+x=0\\3x+18=0\end{aligned}\right.}\\
   \Leftrightarrow {\left[\begin{aligned}x=8\\3x=-18\end{aligned}\right.}\\
   \Leftrightarrow {\left[\begin{aligned}x=8\\x=\frac{-18}{3}\end{aligned}\right.}\\$

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