A= -1^2 + 2^2 - 3^2 + 4^2-.....- 99^2 + 100^2
=(2-1)(2+1)+(4-3)(4+3)+...+(100-99)(100+99)
=1+2+3+4+...+99+100
=(100+1).100:2=5050
tính
A) A= -1^2+2^2-3^2+4^2...99^2+100^2
b) B= -1^2+2^2-3^2+4^2...+(-1)^n.n^2
1; tính
a) A= -1^2+2^2-3^2+4^2...99^2+100^2
b) B= -1^2+2^2-3^2+4^2...+(-1)^n . n^2
tinh A=1+ 1/2 +1/(2*3) +1/(3*4)+...+1/(99*100)+100
1-a,\(A=\frac{1}{1+\sqrt{2}}+\frac{1}{\sqrt{2}+\sqrt{3}}+\frac{1}{\sqrt{3}+\sqrt{4}}+...+\frac{1}{\sqrt{n-1}+\sqrt{n}}\)
b,\(B=\frac{1}{2+\sqrt{2}}+\frac{1}{3\sqrt{2}+2\sqrt{3}}+\frac{1}{4\sqrt{3}+3\sqrt{4}}+...+\frac{1}{100\sqrt{99}+99\sqrt{100}}\)
Tính A = -1^2 -2^2 - 3^2 + 4^2 -5^2 -6^2 - 7^2 +8^2 -...-99^2 +100^2?
Tính A = -1^2 -2^2 - 3^2 + 4^2 -5^2 -6^2 - 7^2 +8^2 -...-99^2 +100^2?
tính
1^2+3^2+5^2+.....+97^2+99^2
1^2-2^2+3^2-4^2+5^2-...........-98^2+99^2-100^2
\(A=\frac{1}{2}+\frac{2}{2^2}+\frac{3}{2^3}+...+\frac{99}{2^{99}}+\frac{100}{2^{100}}\). So sánh A với 2
Tính : A =-1^2+2^2-3^2+4^2-...-99^2+100^2 B= -1^2+2^2-3^2+4^2-...+(-1)^n.n^2
