Program HOC24;

var i,n: integer;

S: real;

begin

write('Nhap n: '); readln(n);

s:=0;

for i:=1 to n do s:=s+(1+1/sqr(i));

write('Gia tri cua bieu thuc do la: ',s:6:2);

readln

end.

 1/N = 1: (1/2 +1/3 + 1/4 + .....+ 1/10)
=> 1/N = 2+3+4+...+10
=> 1/N= (10+2). 9/2= 54
=> N = 1/54

   nhớ k cho mình nha :33

a: \(A=0x^2y^4z+\dfrac{7}{2}x^2y^4z-\dfrac{2}{5}x^2y^4z=\dfrac{31}{10}x^2y^4z=\dfrac{31}{10}\cdot2^2\cdot\dfrac{1}{16}\cdot\left(-1\right)=-\dfrac{31}{40}\)

a: \(=\dfrac{7}{5}x^4z^3y=\dfrac{7}{5}\cdot2^4\cdot\left(-1\right)^3\cdot\dfrac{1}{2}=-\dfrac{56}{5}\)

b: \(=-xy^3\)

 bbgfhfygfdsdty64562gdfhgvfhgfhhhhh

\hvhhhggybhbghhguyg

Ta có: \(a=\left(2x-1\right)^2+\left(2x+1\right)^2+2\left(4x^2-1\right)\)

\(=\left(2x-1+2x+1\right)^2\)

\(=16x^2=16\cdot\dfrac{1}{16}=1\)

\(B=m^2-mn+m-n^2-n+mn=m^2-n^2+n-n\\ =\left(m-n\right)\left(m+n+1\right)\\ =\left(-\dfrac{2}{3}+\dfrac{1}{3}\right)\left(-\dfrac{2}{3}-\dfrac{1}{3}+1\right)=-\dfrac{1}{3}\cdot0=0\)

\(B=m\left(m-n+1\right)-n\left(n+1-m\right)=m^2-mn+m-n^2-n+mn=m^2-n^2+m-n=\left(m-n\right)\left(m+n\right)+\left(m-n\right)=\left(m-n\right)\left(m+n+1\right)=\left(-\dfrac{2}{3}+\dfrac{1}{3}\right)\left(-\dfrac{2}{3}-\dfrac{1}{3}+1\right)=-\dfrac{1}{3}.0=0\)