88 (1-1 / 3 × 2),

88 (1-1 / 3 × 2),

0.88÷（1-1/3×2）
＝0.88÷1/3
＝0.88×3
＝2.64

Simple calculation of 1420 × 3.4 + 1.42 × 2300 + 14.2 × 430

1420×3.4+1.42×2300+14.2×430
=142*34+142*23+142*43
=142（34+23+43)
=142*100
=14200

5% 4 * 0.8 + 80 * 5% 3-5% 4 * 0.4

5% 4 * 0.8 + 80 * 5% 3-5% 4 * 0.4
=4 out of 5 * 0.8 + 4 out of 5 * 0.6-4 out of 5 * 0.4
=4 out of 5 * (0.8 + 0.6-0.4)
=4 / 5 * 1
=4 out of 5

LIM (1 / x2 + cos1 / x), X tends to be positive infinity

1 / x2 tends to 0
Cos1 / X tends to 1
So the answer is 1

The area of the circle is equal to that of the rectangle. If the radius of the circle is known to be 2 cm, the area of the shadow part can be calculated
Cut off the shadow. One quarter of the area of this circle is the shadow

Is the graph like this?
Because the area of a circle is equal to that of a rectangle, the area of the shaded part is three fourths of the area of the circle
 
Area of circle = 3.14 × 2 & # 178; = 12.56 (square centimeter)
Shadow area = 12.56 × (1-1 / 4) = 9.42 (cm2)

If √ x is a real number, then the range of function y = x & sup2; + 3x-5 is?

X is a real number
x>=0
y=(x+3/2)²-29/4
Axis of symmetry x = - 3 / 2, opening upward
So to the right of x = - 3 / 2 is an increasing function
So when x = 0, the minimum is y = - 5
So the range [- 5, positive infinity)

Inverse function of sin and 1 / sin
We know that the inverse function of sin is sin ^ - 1 (x),
Is sin ^ - 1 (x) the same as 1 / sin (x),
If not, please explain. Thank you

Sine function y = SiNx, when x ∈ (- π / 2, π / 2), there is an inverse function. The inverse function is: y = arcsinx, XX ∈ (- 1,1). Do sin ^ - 1 (x) and 1 / sin (x) have the same meaning? The answer to this question is: of course. Because the negative 1 power is its reciprocal. Formula: x ^ (- 1) = 1 / x, but your first

Saw a 2 / 3M wide wooden strip from a rectangular board with an area of 12 square meters, and the remaining area is 9 square meters. Calculate the remaining perimeter?

I'm in grade two. Maybe you don't understand? What grade is this
Let the length be x meters and the width be y meters
(X-2/3)Y=9 ①
XY=12 ②
From (2)
X=12/Y ③
Bring (3) into (1),
12-2/3Y=9
2/3Y=3
Y=4.5④
Bring (4) into (3)
X=8/3
(8/3-2/3+4.5)*2=6.5*2=13
A: the remaining perimeter is 13 meters
Can you take a look?

I want it from Jiangsu Education Press

34. The passenger car and the freight car leave from a and B at the same time, and meet 4 hours later. Given that the speed ratio of the passenger car and the freight car is 7:5, how many hours does it take for the freight car to arrive at a after meeting?
Set a hour for the truck to arrive at a place
5/12：4=7/12：a
5/12a=7/12×4
A = 28 / 5 hours
35. There are several red and white balls. The ratio of red and white balls is 5:7. Later, there are six red balls. At this time, the ratio is 1:1. How many balls are there now?
Let there be 5 a red ball and 7 a white ball
According to the meaning of the title
（5a+6）：7a=1：1
7a=5a+6
2a=6
a=3
Now there are (5 + 7) × 3 + 6 = 42
36. There are 85 people in class A and class B. one eleventh of class B is transferred to class A. the ratio of class A and class B is 9:8. How many people in class a?
If there are a students in class A, then there are 85-a students in class B
[a+（85-a）×1/11]：（85-a）×（1-1/11）=9：8
8a+8/11×（85-a）=90/11×（85-a）
88a+680-8a=7650-90a
170a=6970
a=41
There are 41 students in class A
37. Class a donated 2 / 3 of class B, class C and class B donated 2 / 5 of class A, class C and class C. if class A and class B donated 144 yuan in total, how much did class C donate?
If class a donates a yuan, class B donates 144-a yuan
Class C donated (144-a) / (2 / 5) - a = 360-7 / 2A yuan
According to the meaning of the title
a=（144-a+360-7/2a）×2/3
3a=288-2a+720-7a
12a=1008
A = 84 yuan
Then class C donated 360-7 / 2 × 84 = 66 yuan
38. The sum of the simplest fractions of the same two molecules is 1 and 7 / 18. The ratio of the two denominators is 2:3. What are the two fractions?
Let the denominator be 2a and 3a respectively
that
1/（2a）+1/（3a）=25/18
5/（6a）=25/18
a=3/5
So these two scores are 5 / 6 and 5 / 9 respectively
reference resources

1 / (1-x) ^ 2 for indefinite integral; X times the root sign (1 + 2x ^ 2) for indefinite integral; X / root sign (1-x ^ 2) for indefinite integral

1、∫dx/(1-x)^2=∫d(x-1)/(x-1)^2=-1/(x-1)+C2、∫x√(1+2x^2)dx=1/4*∫√(1+2x^2)d(1+2x^2)=1/4*2/3*(1+2x^2)^(3/2)+C=1/6*(1+2x^2)^(3/2)+C3、∫xdx/√(1-x^2)=-1/2*∫d(1-x^2)/√(1-x^2)=-1/2*2*√(1-x^2)+C=-√...