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If 3x + 2Y = 0, find (1 - X / x + y + 2Y ^ 2 / x ^ 2-y ^ 2) / (1 + 2Y / X-Y)
The original formula = [(x + y) / (x + y) - X / (x + y) + 2Y & # 178; / (x + y) (X-Y)] / (X-Y + 2Y) / (X-Y)
=[y/(x+y)+2y²/(x+y)(x-y)]×(x-y)/(x+y)
=(xy-y²+2y²)/(x+y)(x-y)×(x-y)/(x+y)
=y(x+y)/(x+y)×1/(x+y)
=y/(x+y)
Factorization: the square of 2 (X-2) - 3x + 6 = 0
=2(x^2-4x+4)-3x+6
=2x^2-8x+8-3x+6
=2x^2-11x+14
=(x-2)(2x-7)
Sum: SN = 1 + 2x + 3x2 + +nxn-1．
When x = 0, Sn = 1; when x = 1, Sn = 1 + 2 + 3 + +When x ≠ 1 and X ≠ 0, Sn = 1 + 2x + 3x2 + +nxn-1，①xSn=x+2x2+3x3+… +nxn．②（1-x）Sn=1+x+x2+x3+… +When xn-1-nxn = 1 − xN1 − x − NxN, x = 0, the above formula is also true, ｜ Sn = 1 − xn (1 − x) 2 − nxn1 − x.x ≠ 1. ｜ Sn = 1, x = 0n (n + 1) 2, x = 11 − xn (1 − x) 2 − nxn1 − x, X ≠ 0, X ≠ 1
80% x + 2 / 5 = 0.8, 1 / 2 x + 15% x = 39 / 20
Urgent request!
80% x + two fifths = 0.8
0.8x=0.8-2/5
0.8x=0.4
x=0.4÷0.8
x=0.5
Half x + 15% x = 39 / 20
0.65x=39/20
x=39/20÷0.65
x=3
Do not understand can ask, help please adopt, thank you!
Subtract the quotient of 114 divided by 13 from the reciprocal of 223. What's the difference?
The reciprocal of 223 is 38, 38-13 △ 114, = 38-13 × 45, = 38-415, = 13120; a: the difference is 13120
2x/0.3+8/3-(1.4-3x)/0.2=0
We need to work it out one by one!
2X / 0.3 + 8 / 3 - (1.4-3x) / 0.2 = 0 simplification: 2x / (3 / 10) + 8 / 3 - (1.4-3x) / (1 / 5) = 0 20x / 3 + 8 / 3-5 (1.4-3x) = 0 (20x + 8) / 3 = 5 (1.4-3x) 20x + 8 = 3 (7-15x) 20x + 8 = 21-45x 20x + 45x = 21-8 65x = 13 x = 13 △ 65x = 0.2
The following questions (calculated by a simple method)
975-147-23 134x8+8x66 125x64 365x99 3000/125/8 99x25 6x75+6x25
25x24 12x15 all with simple algorithm layer calculation. Fast, please
975-147-23
=975-(147+23)
=975-170
=805
134x8+8x66
=8x(134+66)
=8x200
=1600
125x64
=125x8x8
=1000x8
=8000
365x99
=365x(100-1)
=36500-365
=36135
3000/125/8
=3000/(125x8)
=3000/1000
=3
99x25
=(100-1)x25
=2500-25
=2475
6x75+6x25
25x24
=25x4x6
=100x6
=600
12x15
=(10+2)x15
=150+30
=180
In 1-200 natural numbers, what is the sum of only three divisors?
A number with only three divisors is the square of a prime number
2²=4
3²=9
5²=25
7²=49
11²=121
13²=169
So sum = 4 + 9 + 25 + 49 + 121 + 169 = 377
Solve the equation (quadratic-4x + 8 of x) (quadratic-4x of x) = 0
Simple classification discussion:
In general, C is too large, so there is no solution
X & # 178; - 4x = 0, X1 = 4, X2 = 0 is the final answer
Building lord!
You can use the law of addition to find 1 + 2 + 3 + 4 Is the sum of 49 + 50
You can think like this: 1 + 49 = 50, 2 + 48 = 50, 3 + 47 = 50 until 24 + 26 = 50, then there are 24 50 from 1 to 24. But there are also 25 and 50, then the result should be: 24 times 50 + 25 + 50 = 1275
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