CMR:
a/\(55^{n+1}-55n\) chia hết cho 54 với mọi\(x\in N\)
Ta có \(55^{n+1}-55^n=......................\)
b/\(n^2\left(n+1\right)+2n\left(n+1\right)\) luôn chia hết cho 6 với mọi số nguyên n.
Ta có:\(n^2\left(n+1\right)+2n\left(n+2\right)=.......\)
c/\(2^{n+2}+2^{n+1}+2^n\) chia hết cho 7,với mọi\(x\in N\).
Ta có:\(2^{n+2}+2^{n+1}+2^n=...\)
Tìm x,biết:
a/\(x+5x^2=0\Leftrightarrow......\)
b/\(x+1=\left(x+1\right)^2\Leftrightarrow..........\)
c/\(x^3+x=0\Leftrightarrow.......\)
d/\(5x\left(x-2\right)-\left(2-x\right)=0\)
e/\(x\left(2x-1\right)+\frac{1}{3}-\frac{2}{3}x=0\Leftrightarrow........\)
g/\(x\left(x-4\right)+\left(x-4\right)^2=0\Leftrightarrow.....\)
h/\(x^2-3x=0\Leftrightarrow.....\)
i/\(4x\left(x+1\right)=8\left(x+1\right)\Leftrightarrow.....\)