If (a-b) / (a + b) is not equal to 1, it is proved that a / B is a rational number

If (a-b) / (a + b) is not equal to 1, it is proved that a / B is a rational number

Suppose (a-b) / (a + b) = 1
Then multiply both sides by (a + b), and the equation is A-B = a + B
We get b = 0
Because when B = 0, a / B is meaningless
So when (a-b) / (a + b) cannot be equal to 1, a / B is meaningful and rational
The above is for reference only, if there is improper, please correct!

If a denotes a rational number, then one part of a is called

Countdown

The following statement is incorrect ()
A. - 3.14 is a negative number, a fraction, and a rational number. B. 0 is neither a positive number nor a negative number, but the integer C. - 2000 is both a negative number and an integer, but not a rational number. D. 0 is not a positive number

According to the meaning of the question: - 2000 is not only a negative number, but also an integer, but it is also a rational number, so choose C

（3a2-2a-5）+（______） =a2-7a+9．

A2-7a + 9 - (3a2-2a-5) = - 2a2-5a + 14, so the missing item should be: - 2a2-5a + 14

The bottom of a triangle remains unchanged. How many times does the height and area of a triangle increase?

The base of a triangle remains unchanged, and the height and area of the triangle are expanded by five times

Find the square of the domain. Y = loga ^ (1-x)
log7^3√49=

1. From the true number greater than 0
The results show that: (1-x) ^ 2 > 0
Then the domain {x | x is not equal to 1}
2.log(7^3)[√49]
=log(7^3)(7)
=(1/3)log7(7)
=1/3

To make a 256 cubic decimeter square bottomless water tank, its height is () decimeter

Let: the side length of square bottom be a, the height be h, v = a ^ 2 × H = 256
Because it is an open water tank:
S table = a ^ 2 + 4ah = a ^ 2-4ah + 4H ^ 2 + 8ah-4h ^ 2
=(a-2h)^2+4h(2a-h)
When a = 2h, the s table is the smallest, that is, the least material
V=(2h)^2×h=4h^3=256
h=4
When its height is (4) decimeters, it saves the most material

As shown in the figure, in △ ABC, D is the midpoint of AC, e is a point on the extension line of segment BC, and the parallel line passing through point a as be intersects with the extension line of segment ed at point F··
As shown in the figure, in △ ABC, D is the midpoint of AC, e is a point on the extension line of line BC, the parallel line passing through point a as be intersects with the extension line of line ed at point F, connecting AE and cf. if AC = EF, try to judge that the quadrilateral aecf is a rectangle

Certification:
The midpoint of AC in ABC is d
The line through point a is parallel to BC
Extend BC to point E
The straight line passing through point E, point D and crossing point a is point F
∵ AF ∥ CE, D is the midpoint of AC
∴∠ADF=∠CDE,∠CED=∠AFD,AD=DC
∴AF=CE
∵ AC = EF, D is the midpoint of AC
∴FD=DE=AD=DC
The parallelogram is a rectangle

Given that the coordinates of points a and B are (4,0) (2,2) respectively, and that point m is a moving point on the ellipse x ^ 2 / 25 + y ^ 2 / 9 = 1, then the minimum value of | Ma | + | MB | is?

10-2 * (root 10), using the concept of ellipse, the sum of the distances to two focal points is a constant, Ma is changed to 10 minus the distance from m to another focal point (- 4,0), then Ma + MB = 10 + mb-mc = 10 - (mc-mb), and the maximum value of (mc-mb) can be obtained. From the triangle trilateral relationship in the image, the maximum value of ~ is BC, that is, the result of the calculation~

In rectangular paper ABCD, ab = 5, ad = 3, fold the paper so that point B falls on B 'on the edge CD, the crease is AE, and the crease is AE,
If there is a point P on the crease AE, the distance from edge CD is equal to the distance from point B, then the equal distance is?

AD=3,AB′=4,DB′=√7
BE=EB′=x
CE=3-x,CB′=4-√7
x²=（3-x）²+（4-√7）²
x=（16-4√7）/3、
PB′‖BC
∠BEP=∠EPB′
∠BEP=∠B′EP
∠EPB′=∠B′EP
PB′=B′E=BE==（16-4√7）/3