X + 2 x X + 3 x X + 4 x X = 50
Tính:
a.[100/3]+[100/3^2]+[100/3^3]+[100/3^4]
b.[50/2]+[50/2^2]+[50/2^3]+[50/2^4]+[50/2^5]
c.[x]+[x+2/3]+[x+4/3]+[x+7/3]+[x+10/3] với x=-2,7
(50- 3 x X ) : 4 x2 -30 : 2 +2 x 7 =21
A = 33...3/50 chữ số 3 x 99...9/50 chữ số 9
( X + 2 ) + ( X+ 4) + ... + (X + 1996) = 99800
(x+2)+(x+4)+...+(x+1996) = 99800
=> (x+x+x+...+x)+(2+4+...+1996) = 99800
=> 998x + 997002 = 99800
998x = 99800 - 997002
998x = -897202
x = -897202 : 998
x = -899
cho x1+x2+x3+x4+...+x49+x50+x51=0 và x1+x2=x3+x4=...=x47+x48=x49+x50=x50+x51=1. tính x50
Tìm X
A. (X +1)+(X+2)+(X+3)+…+(X+ 100)=5750
B. X+(1+2+3+4+…+50)=2000
C. (X-1)+(X-2)+…+(X-100)=50
\(c,\)\(\left(x-1\right)+\left(x-2\right)+....+\left(x-100\right)=50\)
\(\left(x+x+...+x\right)-\left(1+2+...+100\right)=50\)
\(100x-5050=50\)
\(100x=50+5050\)
\(100x=5100\)
\(\Rightarrow x=\frac{5100}{100}=51\)
\(a,\left(x+1\right)+\left(x+2\right)+\left(x+3\right)+....+\left(x+100\right)=5750\)
\(\left(x+x+x+...+x\right)+\left(1+2+3+...+100\right)=5750\)
\(100x+5050=5750\)
\(100x=5750-5050\)
\(100x=700\)
\(\Rightarrow x=7\)
\(b,x+\left(1+2+3+...+50\right)=2000\)
\(x+\frac{\left[1+50\right]\cdot\left[\left(50-1\right)\div1+1\right]}{2}=2000\)
\(x+1275=2000\)
\(\Rightarrow x=2000-1275=725\)
c , ( x - 1 ) + ( x - 2 ) + ...... + ( x - 100 ) = 50
( x + x + ........ + ) - ( 1 + 2 + ..... + 100 ) = 50
100x - 5050 = 50
100x = 50 + 5050
100x = 5100
=> x = 5100/100 = 51
4 x 125 x 25 x 8
2 x 8 x 50 x 25 x 125
2 x 3 x 4 x 5 x 50 x 25
25 x 20 x 125 x 8 - 8 x 20 x 5 x 125
1 x 2 + 2 x 3 + 3 x 4 + 4 x 5 + . . . + 49 x 50
=49x50x51
=124950
trên mạng có CM 1 x 2 + 2 x 3 + 3 x 4+ 4 x 5 + ... + n x (n+1) = n x (n+1) x (n+2)
Tính tổng:
A = 1 x 2 x 3 + 2 x 3 x 4 + 3 x 4 x 5 + ... + 48 x 49 x 50
\(\frac{49\cdot50\cdot51}{3}\)
tinh nhanh
4 x 125 x 25 x 8
2 x 8 x 50 x25 x125
2 x 3 x 4 x 5 x 50 x 25
25 x 20 x 125 x 8 - 8 x 20 x 5 x 125
4 × 125 × 25 × 8
= (4 × 25) × (125 × 8)
= 100 × 1000
= 100 000
2 × 8 × 50 × 25 × 125
= (2 × 50) × (8 × 125) × 25
= 100 × 1000 × 125
= 12 500 000
2 × 3 × 4 × 5 × 50 × 25
= (2 × 50) × (4 × 25) × (3 × 5)
= 100 × 100 × 15
= 150 000
25 × 20 × 125 × 8 - 8 × 20 × 5 × 125
= 8 × 125 × 20 × (25 - 5)
= 1000 × 20 × 20
= 400 000
- (25 x 4) x (125 x8)=100 x 1000 =100000
- (50 x 2) x (8 x 125) x 25=100 x 1000 x 25 =2500000
- (2 x 50 ) x (4 x 25) x (3 x5)=100 x 100 x 15=150000
- 25 x 20 x125 x 8 - 5
= (20 x 5) x (125 x 8) -25=100 x 1000 -5 =100000 - 5 =99995
4 *125*25*8
=4*25*125*8
=100*1000
=100000
2*8*50*25*125
=2*50*8*125*25
=100*1000*25
=2500000
2*3*4*5*50*25
=2*50*4*25*3*5
=100*100*15
=150000
25*20*125*8-8*20*5*125
=25*4*5*125*8-8*125*20*5
=100*1000*5-1000*100
=500000-100000
=400000
=
X + 2 x X + 3 x X + 4 x X = 50
X + 2 x X + 3 x X + 4 x X = 50
X x ( 1 + 2 + 3 + 4 ) = 50
X x 10 = 50
X = 50 : 10
X = 5
X + 2 x X + 3 x X + 4x X = 50
X x ( 1+2+3+4) = 50
X x 10 = 50
X = 50 : 10
X = 5
\(x+2\cdot x+3\cdot x+4\cdot x=50\)
\(x\cdot\left(2+3+4+1\right)=50\)
\(x\cdot10=50\)
\(x=50:10\)
\(x=5\)