2000 / 25

2000 / 25

=(2000×4)/(25×4)
=8000/100
=80

How to divide the elimination method of division term in sequence summation? Is there any formula, for example: 1 / (2n-1) (2n + 1)

Each term of the product of denominators should be an arithmetic sequence an, with tolerance d > 0
The detachable item is (1 / D) (1 / an-1-1 / an)
1/(an*an+1)=1/d((an+1-an)/an*an+1)=1/d(1/an-1/an+1)
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Let f (x) = | 2x + 1 | - | x-4 |, and write its monotone interval
All images

Let f (x) = y, and then solve and draw the image according to the general linear function. The image of this function should be a piecewise function

What is the greatest common factor of 18 and 45______ The least common multiple is______ ．

18 = 2 × 3 × 3; 45 = 3 × 3 × 5; so the greatest common factor of 18 and 45 is: 3 × 3 = 9; the least common multiple is: 2 × 3 × 3 × 5 = 90; so the answer is: 9; 90

Given that a and B are positive numbers and ab = a + B + 3, then the minimum value of AB is______ ．

∵ a, B are positive numbers, and ab = a + B + 3 ≥ 2Ab + 3, ∵ ab-2ab-3 = (ab-3) (AB + 1) ≥ 0, ∵ ab ≥ 3, ∵ ab ≥ 9, so the minimum value of AB is 9, so the answer is: 9

Sum: 1 + 2x + 3x ^ 2 +... + NX ^ (n-1)

Multiply X by common ratio dislocation subtraction method to get xsn = x + 2x ^ 2 + 3x ^ 3 +By subtracting NX ^ n, we get (1-x) Sn = 1 + X + x ^ 2 + x ^ 3 +X ^ (n-1) - x ^ n, Sn = (1 + X + x ^ 2 + x ^ 3 +x^(n-1)-x^n)/(1-x) =[(1-x^n)/(1-x)-x^n]/(1-x)=(1-x^n)/(1-x)^2-x^n/(1-x) =(1-x^n)/(...

7 / 13 × 39

"7/13×39=7×3=21

What's the difference by subtracting the quotient of 134 divided by 13 from the reciprocal of 123?

1 △ 123-13 △ 134, = 1 × 35-13 × 47, = 35-421, = 43105; a: the difference is 43105

3 / 4 [4 / 3 (4x-1) + 8] = 7 / 3 + 2x / 3

Solution equation: 3 / 4 [4 / 3 (1 / 4 x-1) + 8] = 7 / 3 + 2x / 3
Simplify 3 / 4 (1 / 3-4 / 3 + 8) = 7 / 3 + 2x / 3
Simplify 1 / 4 X-1 + 6 = 7 / 3 + 2x / 3
2X / 3-4x / 4 = 7 / 5-3
Simplify 5 / 12 x = 8 / 3
Results x = 6.4

A simple method of multiplying 1003 by 23 minus 69

1003 times 23 minus 69
=1003x23-23x3
=23x(1003-3)
=23x1000
=23000