As shown in the figure, fold a rectangular piece of paper ABCD along AF to make point B fall at B ′. If ∠ ADB = 20 °, then how many degrees should ∠ BAF be to make ab ′‖ BD?

∵ the rectangular paper piece ABCD is folded along AF, so that the B point falls at B ′, ∵ B ′ - AF = ∵ BAF, ∵ ab ′ - BD, ∵ B ′ - ad = ∵ ADB = 20 °, ∵ B ′ - AB = 20 ° + 90 ° = 110 °, ∵ BAF = 110 °△ 2 = 55 °. The ab ′ - BD can be made only when the ∵ BAF is 55 degrees

As shown in the figure, fold a rectangular strip of paper ABCD along AF. if ∠ ADB = 22 °, then what is the degree of ∠ BAF to make ab '‖ BD

∵∠B'=∠B=90°,AB'∥BD,
∴B'F⊥BD,
Let b'f intersect with ad in E, and ∠ def = 90 ° - 22 ° = 68 °,
∴∠BFE=∠DEF=68°,
It can be seen from the folding: ∠ AFB = ∠ AFB '= 1 / 2 ∠ BFE = 34 °,
∴∠BAF=90°-∠AFB=56°.
A: when ∠ BAF = 56 °, ab '‖ BD

When a rectangular strip of paper ABCD is folded along AF and ∠ ADB = 28 ° is known, then how many degrees is ∠ BAF to make AE and BD parallel to each other

∵ the rectangular piece of paper ABCD is folded along AF to make point B fall at B ′,
∴∠B′AF=∠BAF,
∵AB′∥BD,
∴∠B′AD=∠ADB=28°,
∴∠B′AB=28°+90°=118°,
∴∠BAF=118°÷2=59°．
The ab ′‖ BD can be achieved only when the ﹥ BAF is 59 degrees

Inverse function of y = 1 + 10 ^ x
And the inverse function of y = 2x + 1 / x + 3

The inverse function of y = 1 + 10 ^ x y = LG (x-1) domain (1, positive infinity)
The inverse function of y = (x + 3) / (2x + 1) is y = (3-x) / (2x-1) and the domain x is not equal to 1 / 2

Finding the inverse function of F (x) = LG (x + 1) / (1-x)

Attention upstairs, LG, not LN
y=f(x)=lg[(1+x)/(1-x)]
(1+x)/(1-x)=10^y
10^y-10^yx=x+1
(10^y+1)x=10^y-1
x=(10^y-1)/(10^y+1)
The inverse function is y = (10 ^ x-1) / (10 ^ x + 1)

Function f (x) = {LG (1-x) (0

This is a piecewise function
The domain of definition is symmetric about the origin, and f (0) = LG (1-0) = 0 can continue to judge
When x belongs to 0

The inverse function of y = (AX + b) / (Cx + D) is y = (1 + 2x) / (3 + 4x)
Let the inverse function of y = (AX + b) / (Cx + D) (a, B, C, D are constants) be y = (1 + 2x) / (3 + 4x), then the value of a, B, C, D is?
A）a=3,b=-1,c=-4,d=2
B）a=-3,b=1,c=4,d=-2
C）a=1,b=2,c=3,d=4
D）a=3,b=4,c=1,d=2
I figured out that it was AB, but the answer in the book was a. why not choose B,

The substitution of a and B into the functional formula is the same. B is the numerator denominator of a and multiplied by - 1. Therefore, a and B are both right. There may be a typographical error in the book, which makes b the correct answer~

What is the power of root 2 of root 2? (√ 2 √ 2)
Urgent+++++++++++++++

The second power of root 2 is
Quarter power of 2
The root two equals 1.414
1.2*1.2=1.44
So the final value is about 1.2

How to solve the inverse function y = x / 3x + 5,

y. X interchange

It is known that quadratic function f (x) = ax * + BX + C and primary function g (x) = - BX, where a, B and C belong to R and satisfy a > b > C, f (1) = 0. * = 2
It is known that quadratic function f (x) = ax * + BX + C and primary function g (x) = - BX, where a, B and C belong to R and satisfy a > b > C, f (1) = 0. * = 2
(1) It is proved that the images of functions f (x) and G (x) intersect at two different points a and B
(2) If the minimum value of F = f (x) - G (x) on [2,3] is 9 and the maximum value is 21, the values of a, B and C are obtained

F(x)=f(x)-g(x)=ax²+2bx+c=ax²-2（a+c）x+c
Axis of symmetry x = 2 (a + C) / 2A = 1 + C / A
According to (1), a > 0, C / a < 1
The axis of symmetry is in x < 2
When x = 2, the minimum value f (2) = 9; when x = 3, the maximum value f (3) = 21
∴4a-4（a+c）+c=9
9a-6（a+c）+c=21
The solution of the equations is: C = - 3, a = 2
∴b=1

As shown in the figure, fold a rectangular piece of paper ABCD along AF to make point B fall at B ′. If ∠ ADB = 20 °, then how many degrees should ∠ BAF be to make ab ′‖ BD?