2X-4 (80-x) = 52

2X-4 (80-x) = 52

Solution: 2x-320 + 4x = 52
2x+4x=52+320
6x=372
x=372÷6
x=62

Please explain it. Thank you
1. If (2x + 2) & sup3; - 1 = 37 / 27, then X=
A. One in nine B. one in six C. two in nine D. minus two in nine
2. If there are two points a (- 3,1) and B (3,1) in the plane rectangular coordinate system, the number of points on the coordinate axis which are equal to the distance between a and B is
A. 1 B. 2 C. 3 d. infinitely many
3. In the plane coordinate system, the coordinate of point O is (3-A, 2A + 6), and the distance between point P and two coordinate axes is equal, then the coordinate of point P is (3-A, 2A + 6)
A. (4,4) B. (- 4,4) C. (4,4) or (12, - 12) d. (12, - 12)
4. If M is the square root of 9 and N = (√ 3) & sup2;, then the relation between M and N is
A.|m|=|n| B.m＞n C.m=n D.m=-n
5. Given that P (2x + y, X-Y) and Q (5, - 1) reflect axially about X axis, then
A.x=-2 ,y=1 B.x=2,y=-1
C.x=2,y=1 D.x=-2,y=-1

1.（2x+2)³-1=37/27
（2x+2)³=64/27
2x+2=4/3
The solution is x = - 1 / 3
The title is right? In fact, as long as you match 64 / 27, you should know that it is 4 / 3 cubic
2. Connecting two points a and B, we can know that the midpoint coordinates of AB line segment are (0,1), passing through (0,1) point, make a straight line perpendicular to AB, the distance from the point on this straight line to a and B is equal, and this straight line is exactly Y axis, so the distance from the point on Y axis to a and B is equal, the answer is d
3. What's the relationship between P and o?
The square root of 9 is ± 3, so choose a
5. Connecting Q and origin o, we can see that the slope of OQ is - 1 / 5. In this question, he wants you to choose D, because when you choose D, the coordinates of P point are (- 5, - 1), but the concept of "axial reflection" is not used properly. According to the meaning of the question, everything is X-Y

2²/1×3+4²/3×5+6²/5×7+8²/7×9+...+20²/19×20

According to the law, the last number should be. + 20 & # 178 / 19 × 21
2²/1×3+4²/3×5+6²/5×7+8²/7×9+...+20²/19×21
=4/1×3+16/3×5+36/5×7+64/7×9+...+400/19×21
=1+1/1×3+1+1/3×5+1+1/5×7+1+1/7×9+...+1+1/19×21
=1×10+1/2(1-1/3+1/3-1/5+1/5-.-1/21)
=10+1/2×20/21
=10 and 10 / 21

Lim tends to infinity x ^ 2-1 / 2x ^ 2-x-1

Lim tends to infinity x ^ 2-1 / 2x ^ 2-x-1
=Lim tends to infinity (x + 1) (x-1) / (x-1) (2x + 1)
==Lim tends to infinity (x + 1) / (2x + 1)
=1/2

The common factor of the polynomial am ^ 2-4a and the polynomial m ^ 2-4m + 4 is

am²-4a
=a(m²-4)
=a(m+2)(m-2)
m²-4m+4=(m-2)²
The common factor of ｛ am & ｛ 178; - 4A and M & ｛ 178; - 4m + 4 is m-2

Fill 1 / 15,7 / 3,12 / 7,15 in brackets to form a simple operation that can be calculated by the law of multiplicative distribution

（1/15）÷（7/3）＋（12/7）÷（15）
=1/15x3/7+12/7x1/15
=1/15x(3/7+12/7)
=1/15x15/7
=1/7
If you don't understand this question, you can ask. If you are satisfied, please click "select as satisfactory answer"

The form of special solution of differential equation y "- 2Y '= x

The corresponding homogeneous linear equation is y '' - 2Y '= 0, the characteristic equation is R ^ 2-2r = 0, r = 0 or 2
X = x * e ^ (0 * x), λ = 0 is the single root of characteristic equation, so the special solution of non-homogeneous linear equation can be set as X * (AX + b) * e ^ (0 * x) = ax ^ 2 + BX, a, B are arbitrary real numbers

Inequality system (2x-3) (3x + 2) 0, no real number solution, find the value range of real number a

a>=3/2

0.35 △ 0.56 = vertical

(1 / 3) when solving LIM (arcsinx / x) ^ (1 / x ^ 2), the lobita rule is used for the first time when transforming e ^ (1 / x ^ 2) ln (arcsinx / x)

limx(arcsinx/x)^(1/x^2)
=e^lim x->0[ln(arcsinx/x)]/x^2
limx->0[ln(arcsinx/x)]/x^2
Using the equivalent infinitesimal band for ln (arcsinx / x) = (arcsinx-x) / X
limx->0[ln(arcsinx/x)]/x^2=lim(arcsinx-x)/x^3
lim(arcsinx-x)/x^3=1/6