lam ho mk voi a ( bai 5) Question lam ho mk voi a ( bai 5) in progress 0 Môn Toán Ben Gia 4 years 2020-10-16T03:50:18+00:00 2020-10-16T03:50:18+00:00 2 Answers 93 views 0
Answers ( )
\(\begin{array}{l}
a){a^3} + 3.{a^2}.4 + 3.a{.4^2} + {4^3}\\
= {\left( {a + 4} \right)^3}\\
b. – \left( {{b^3} – 3.{b^2}.2 + 3.b.4 – {2^3}} \right)\\
= – {\left( {b – 2} \right)^3}\\
c.{\left( {m – n} \right)^6} – 3.{\left( {m – n} \right)^4}.2 + 3.{\left( {m – n} \right)^2}.4 – {2^3}\\
= {\left[ {{{\left( {m – n} \right)}^2} – 2} \right]^3}\\
d.{\left( {\dfrac{2}{3}a} \right)^3} – 3.{\left( {\dfrac{2}{3}a} \right)^2}.2b + 3.\left( {\dfrac{2}{3}a} \right).4{b^2} – {\left( {2b} \right)^3}\\
= {\left( {\dfrac{2}{3}a – 2b} \right)^3}
\end{array}\)
Đáp án:
d. \({\left( {\dfrac{2}{3}a – 2b} \right)^3}\)
Giải thích các bước giải:
\(\begin{array}{l}
a){a^3} + 3.{a^2}.4 + 3.a{.4^2} + {4^3}\\
= {\left( {a + 4} \right)^3}\\
b. – \left( {{b^3} – 3.{b^2}.2 + 3.b.4 – {2^3}} \right)\\
= – {\left( {b – 2} \right)^3}\\
c.{\left( {m – n} \right)^6} – 3.{\left( {m – n} \right)^4}.2 + 3.{\left( {m – n} \right)^2}.4 – {2^3}\\
= {\left[ {{{\left( {m – n} \right)}^2} – 2} \right]^3}\\
d.{\left( {\dfrac{2}{3}a} \right)^3} – 3.{\left( {\dfrac{2}{3}a} \right)^2}.2b + 3.\left( {\dfrac{2}{3}a} \right).4{b^2} – {\left( {2b} \right)^3}\\
= {\left( {\dfrac{2}{3}a – 2b} \right)^3}
\end{array}\)