\(\left(x-1\right)^4=81\)
\(\Rightarrow\left(x-1\right)^4=\left(\pm3\right)^4\)
\(\Rightarrow\orbr{\begin{cases}x-1=3\\x-1=-3\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=4\\x=-2\end{cases}}\)
vậy___
a - (- 351) - (621 + 451 - 821)
= a + 351 - 621 - 451 + 821
= a - (451 - 351) + (821 - 621)
= a - 100 + 100
= a - 0
= a
1,\(\left(x-1\right)^4=81\)
\(\Rightarrow\left(x-1\right)^4=\orbr{\begin{cases}3^4\\\left(-3\right)^4\end{cases}}\)
\(\Rightarrow x-1=\orbr{\begin{cases}3\\-3\end{cases}}\)
\(\Rightarrow x=\orbr{\begin{cases}4\\-2\end{cases}}\)
2,\(a-\left(-351\right)-\left(621+451-821\right)\)
\(=a+351-251\)
\(=a+100\)
\(\left(x-1\right)^4=81\)
\(\Rightarrow\left(x-1\right)^4=3^4\)
\(\Rightarrow x-1=3\)hoặc \(x-1=-3\)
\(\Rightarrow x=3+1\) \(x=-3+1\)
\(\Rightarrow x=4\) \(x=-2\)
Vậy \(x=4\)hoặc \(x=-2\)
Tính nhanh :
\(a-\left(-351\right)-\left(621+451-821\right)\)
\(=a+351-621-451+821\)
\(=a-\left(821-621\right)+\left(451-351\right)\)
\(=a-200+100\)
\(=a+\left(-100\right)\)
