C = \(\frac{1}{2}+\left(\frac{1}{2}\right)^2+...+\left(\frac{1}{2}\right)^{30}\)
\(\frac{1}{2}\).C = \(\left(\frac{1}{2}\right)^2+\left(\frac{1}{2}\right)^3+...+\left(\frac{1}{2}\right)^{31}\)
\(-\frac{1}{2}C=\frac{1}{2}C-C=\left(\frac{1}{2}\right)^{31}-\frac{1}{2}\)
=> C = \(\left[\left(\frac{1}{2}\right)^{31}-\frac{1}{2}\right]:\left(-\frac{1}{2}\right)\)
\(\frac{30}{\sqrt{1-\frac{\left(0.8c\right)^2}{c^2}}}=\frac{30}{\sqrt{1-\frac{0.64c^2}{c^2}}}\)
C = 1/2 + (1/2)2 + ...+ (1/2)30
Tính:
1 + 1/2 (1 +2) + 1/3 (1+2+3) + ... + 1/30 (1+2+3+...+30)
bài 1 :tìm x , biết :
(x-7)^ x+1(x-7)^x+11=0
bài 2 :tìm x , biết :
a,|2x-3| > 5 c,|3x-1| ≤ 7 d,|3x-5| + |2x+3| = 7
bài 3 :
a,tính tổng S = 1 + 5^2 + 5^4 + ....... + 5^200.
b,so sánh 2^30 + 3^30 + 4^30 và 3.24^10
f(x)=x^2/1-2x+2 x^2 tính a=f(1/30)+f(2/30)+..+f(29/30
: Tìm x, biết:
a) 3x( 4x- 1) - 2x(6x- 3 )=30 b) 2x(3-2x) + 2x(2x-1)=15
c) (5x-2)(4x-1) + (10x +3)(2x - 1)=1 d) (x+2) (x+2)- (x -3)(x+1) = 9
e) (4x+1)(6x-3) = 7 + (3x – 2)(8x + 9) g) (10x+2)(4x- 1)- (8x -3)(5x+2) =14
Tinh hop li:
a.8/9-1/72-1/56-1/42-1/30-1/20-1/12-1/6-1/2
b.(-1/2)-(-3/5)+(-1/9)+1/127-(+7/18)+4/35-(-2/7)
c.3/5+3/11-(-3/7)+(2/97)-1/35-3/4+(-2/7)
tìm n biết rằng:
a,5^n-1+5^n-2=30
b,2^n+2-3.2^n-1=5.2^4
c.3^2n-1+2.9^n-1=135
Tinh:
\(B=1+\frac{1}{2}.\left(1+2\right)+\frac{1}{3}.\left(1+2+3\right)+\frac{1}{4}.\left(1+2+3+4\right)+...+\frac{1}{30}.\left(1+2+3+4+...+30\right)\)
