cho A= n^6-n^4+2n^3+2n^2 voi n>1. chung minh A khong phai so chinh phuong
cho n la so nguyen duong va d la mot uoc nguyen duong cua 2n\(^2\) chung minh n\(^2\)+d khog phai la so chinh phuong?
chung minh: 3n+63 (n thuoc N ; n khac 0,4) khong la so chinh phuong
Chung minh cac so sau khong phai la chinh phuong:
a] \(2^n-1(n\varepsilonℕ^∗)\)
b} \(3^{3n}+19(n\varepsilonℕ^∗)\)
cho phuong trinh 2x^2+mx+2n+8=0 (voi m;n thuoc Z) gia su phuong trinh co 2 nghiem deu nguyen chung minh m^2+n^2 la hop so
chung minh rang voi moi so tu nhien n >1 thi A=n(n+1)(n+2)....(n+7)+7! khong viet duoc thanh tong 2 so chinh phuong
1, chung minh a3 + 3a3 + 2a +2 khong la so chinh phuong
chung minh : A=2+2\(\sqrt{12n^2+1}\)la so chinh phuong
cho n thuoc N* chung minh (2^2)^10n+1 +19 va (2^3)^4n+1 + 5 la hop so