How to calculate this mathematical reasoning? 2,12,36,80,

How to calculate this mathematical reasoning? 2,12,36,80,

2,12,36,80, (150) two ways of thinking: the original sequence can be transformed into 2 = 2 × 1 ^ 2,12 = 3 × 2 ^ 2,36 = 4 × 3 ^ 2,80 = 5 × 4 ^ 2, according to this law, the unknown term is 6 × 5 ^ 2 = 150

How to calculate this mathematical reasoning? - 2, - 8,0,64,
a,-64 b,128 c,156 d,250

-2 -8 0 64 Z
-1*2^1 -2*2^2 0*2^3 4*2^4 x*2^5
-1 -2 0 4 x
-1*2+0=2
-2*2+4=0
0*2+x=4
x=4
Z = 128 choose B

How to calculate this mathematical reasoning? 14,6,2,0,

Answer: - 1
14÷2-1＝6
6÷2-1＝2
2÷2-1＝0
0÷2-1＝－1

How to calculate the length of a parallelogram is 10, the length of a diagonal is 8, and the value range of the other diagonal is 12-28?

A diagonal line of 8 intersects another diagonal line and is divided into two segments, each of which is 4,
Similarly, the unknown diagonal is divided into two segments,
The length of one of the four parallel lines is 10,
According to the triangle relationship, we can know that the value of one segment of the unknown diagonal is 10 minus 4-10 plus 4, which is 6-14,
In this way, we can know that the value range of the other diagonal is 6 * 2-14 * 2, that is 12-28
You can see by drawing the picture below!

Solving equation 1 / [(1 / 12) + (1 / x)] = 8

1/12 +1/x=1/8
1/x=1/24
x=24

If x circle square + y square + 2x-4y + 1 = 0 is symmetric with respect to line 2aX by + 2 = 0, then one part of a + four parts of B is taken as

(x + 1) & sup2; + (Y-2) & sup2; = 4 a circle is symmetric with respect to a straight line, then the straight line is diameter, so it passes through the center of the circle (- 1,2) - 2a-2b + 2 = 0A + B = 1. If there are negative numbers in a and B, then 1 / A + 4 / B can take all negative numbers. A = - 1 / 3, B = 4 / 3, then 1 / A + 4 / b = 0. If a > 0, b > 0, then 1 / A + 4 / b = (1 / a + 4 / b) (a + b) = 5 + (B / A + 4A / b) > = 5 + 2 √ (b

Fast X / (x-1) = 3 / (square of x-1) + 1

Original formula: (x / x-1) = (3 / (x ^ 2) - 1) + 1
Double times (x + 1) (x-1): X (x + 1) = 3 + (x + 1) (x-1)
Simplification: (x ^ 2) + x = 3 + (x ^ 2) - 1
x=2
The test shows that x = 2 is the root of the original equation
The root of the equation is x = 2
(x ^ 2) is the square of X

It is proved that no matter what real number x takes, the value of 6x-3x & # 178; - 7 is less than 0
Urgent, online, etc

6x-3x²-7
=-3x²+6x-7
=-3(x²-2x) -7
=-3[(x²-2x+1) -1]-7
=-3(x-1)²+3-7
=-3(x-1)²-4≤-4＜0
The value of 6x-3x & # 178; - 7 is less than 0

If x is a rational number which is not equal to 1, we call 1-1 / x the difference reciprocal of X. for example, the difference reciprocal of 2 is 1-2 / 1 = - 1, the difference reciprocal of - 1 is 1 - (- 1) 1 = 2 / 1, it is known that X1 = - 3 / 1, X2 is the difference reciprocal of x1, X3 is the difference reciprocal of X2, X4 is the difference reciprocal of X3 And so on, what is the value of x2015? If X1 = 3, what is the value of x2015?

X1 = - 1 / 3, by calculating x2 = 3 / 4, X3 = 4, X4 = - 1 / 3 = x1, we can get some periodicity, then x2015 = x2 = 3 / 4
If X1 = 3, we can get x2 = - 1 / 2, X3 = 2 / 3. If X4 = 3 = x1, then x2015 = x2 = - 1 / 2

Given that the solution of the system of equations 5x + y = 2 + A, x + 3Y = - 3 + 2A satisfies x + y = 0, the value of the solution is 0

5x+y=2+a （1）
x+3y=-3+2a （2）
If the solution satisfies x + y = 0, then x = - Y
-5Y + y = 2 + A, that is - 4Y = 2 + a (3)
-Y + 3Y = - 3 + 2a, that is, 2Y = - 3 + 2A (4)
(4) X2 + (3): 0 = - 4 + 5a, that is, a = 4 / 5