1.tính nhanh a,(24x^5-9x^3+18x^2):3x b(-4x^2+x^3-20+5x):(x-4) 2.tinh a,(7.3^5-3^4+3^6):3^4 b,(16^3-64^2):8^3 05/08/2021 Bởi Daisy 1.tính nhanh a,(24x^5-9x^3+18x^2):3x b(-4x^2+x^3-20+5x):(x-4) 2.tinh a,(7.3^5-3^4+3^6):3^4 b,(16^3-64^2):8^3
Giải thích các bước giải: Ta có: \(\begin{array}{l}1,\\a,\\\left( {24{x^5} – 9{x^3} + 18{x^2}} \right):3x\\ = \left[ {3x\left( {8{x^4} – 9{x^2} + 6x} \right)} \right]:3x\\ = 8{x^4} – 9{x^2} + 6x\\b,\\\left( { – 4{x^2} + {x^3} – 20 + 5x} \right):\left( {x – 4} \right)\\ = \left[ {\left( {{x^3} – 4{x^2}} \right) + \left( {5x – 20} \right)} \right]:\left( {x – 4} \right)\\ = \left[ {{x^2}\left( {x – 4} \right) + 5\left( {x – 4} \right)} \right]:\left( {x – 4} \right)\\ = \left[ {\left( {x – 4} \right)\left( {{x^2} + 5} \right)} \right]:\left( {x – 4} \right)\\ = {x^2} + 5\\2,\\\left( {{{7.3}^5} – {3^4} + {3^6}} \right):{3^4}\\ = \left[ {{3^4}.\left( {7.3 – 1 + {3^2}} \right)} \right]:{3^4}\\ = 7.3 – 1 + {3^2}\\ = 21 – 1 + 9\\ = 29\\b,\\\left( {{{16}^3} – {{64}^2}} \right):{8^3}\\ = \left[ {{{\left( {2.8} \right)}^3} – {{\left( {{8^2}} \right)}^2}} \right]:{8^3}\\ = \left[ {{2^3}{{.8}^3} – {8^4}} \right]:{8^3}\\ = \left( {{{8.8}^3} – {8^4}} \right):{8^3}\\ = 0:{8^3}\\ = 0\end{array}\) Bình luận
Giải thích các bước giải:
Ta có:
\(\begin{array}{l}
1,\\
a,\\
\left( {24{x^5} – 9{x^3} + 18{x^2}} \right):3x\\
= \left[ {3x\left( {8{x^4} – 9{x^2} + 6x} \right)} \right]:3x\\
= 8{x^4} – 9{x^2} + 6x\\
b,\\
\left( { – 4{x^2} + {x^3} – 20 + 5x} \right):\left( {x – 4} \right)\\
= \left[ {\left( {{x^3} – 4{x^2}} \right) + \left( {5x – 20} \right)} \right]:\left( {x – 4} \right)\\
= \left[ {{x^2}\left( {x – 4} \right) + 5\left( {x – 4} \right)} \right]:\left( {x – 4} \right)\\
= \left[ {\left( {x – 4} \right)\left( {{x^2} + 5} \right)} \right]:\left( {x – 4} \right)\\
= {x^2} + 5\\
2,\\
\left( {{{7.3}^5} – {3^4} + {3^6}} \right):{3^4}\\
= \left[ {{3^4}.\left( {7.3 – 1 + {3^2}} \right)} \right]:{3^4}\\
= 7.3 – 1 + {3^2}\\
= 21 – 1 + 9\\
= 29\\
b,\\
\left( {{{16}^3} – {{64}^2}} \right):{8^3}\\
= \left[ {{{\left( {2.8} \right)}^3} – {{\left( {{8^2}} \right)}^2}} \right]:{8^3}\\
= \left[ {{2^3}{{.8}^3} – {8^4}} \right]:{8^3}\\
= \left( {{{8.8}^3} – {8^4}} \right):{8^3}\\
= 0:{8^3}\\
= 0
\end{array}\)