tim so nguyen x thoa man -210=-1+-2+-3+...+(-x-1)+-x la
DT
Những câu hỏi liên quan
tim so nguyen x thoa man : -210=(-1)+(-2)+(-3)+...+(-x-1)+(-x)
-210 = (-1) + (-2) + .... + (-x - 1) + (-x)
-210 = -[1 + 2 + 3 + ..... + (x + 1) + x]
=> 210 = 1 + 2 + 3 + .... + (x + 1) + x
Áp dụng công thức tính dãy số ta có :
\(\frac{\left[\left(x-1\right):1+1\right].\left(x+1\right)}{2}=210\)
=> x(x + 1) = 420
=> x = 20
Đúng 0
Bình luận (0)
Có -210 = (-1) + (-2) + (-3) +...+ (-x-1) + (-x)
=> -210 = -(1 + 2 + 3 +...+ (x-1) + x)
=> 210 = 1 + 2 + 3 +...+ (x-1) + x
=> 210 = (1+x)x : 2
=> 420 = x(x+1)
=> x = 20
Vậy x = 20. k nha bạn
Đúng 0
Bình luận (0)
tim so nguyen x thoa man -210=(-1)+(-2)+(-3)+...+(-x+1)+(-x)
tim so nguyen x thoa man :
-210=(-1)+(-2)+(-3)+...+(-x+1)+(-x)
a)Tim tat ca cac so nguyen duong x, y , z thoa man: \(\frac{x+y\sqrt{2013}}{y+z\sqrt{2013}}\)la so huu ti, dong thoi x2 + y2+ z2 la so nguyen to.
b) Tim so tu nhien x, y thoa man: x(1+x+x2) = y(y-1).
tim x,y la so nguyen thoa man 1/x +1/y=1/8
Tim 3 so nguyen to lien tiep x,y,z (x<y<z) thoa man A = x^2 + y^2 + z^2 la so nguyen to
cho x,y,z la cac so huu ti duong thoa man x+1/yz y +1/xz z+1/xy la cac so nguyen tim gia tri lon nhat cua bieu thuc A=x+y^2+z^3
1.tim so nguyen to p de 4p+1 la so chinh phuong
2.chung minh rang khong co gia tri x, y nguyen nao thoa man
7x^2- 5y^2=3
1.Tim cac chu so x va y de so 1x8y2 chia het cho 36
2.tim cac gia tri nguyen cua n de phan so A=3.n+2/n-1 co gia tri la so nguyen
3.tim cac chu so x y thoa man
(x-2)^2.(x-3)^2=4
4.tim so tu nhien x biet
(x-5):3/100=20.x/100 +5