Math book 2-3 answers

Uh-

I'm here-

But-there are really many problems-

I: (1)2t-t= 15

(2)a-49%a= 1020

(3)80%b- 10=70

(4)(a-45000)/30=200

2: (1) 4/3-8x = 3-11/2x

-8x+ 1 1/2x

=3-4/3

-5/2

=5/3

=-2/3

(2)0.5x-0.7=6.5- 1.3x

0.5X+ 1.3X=6.5+0.7

1.8X=7.2

X=4

(3) 1/6(3x-6)=2/5x-3

Solution:15/5x-12/5x = 6-18.

3/5x=- 12

1/5x=-4

x=-20

(4)( 1-2x)/3 =(3x+ 1)/7-3

7( 1-2x)= 3(3x+ 1)-3 * 2 1

7- 14x=9x+3-63

23x=67

x=67/23

Three: x-(x- 1)/3=7-(x+3)/5.

x=7/ 13

Four: s = gt 2/2 (the relationship between the distance and time of free fall), 19.6 = g (2 * 2)/2, and g = 9.8m/s squared.

So when t=3, there is s = g (3 2)/2 = 9g/2 = 44.1m.

Five. We can catch up with the slow horse in x days.

240x= 150( 12+x)

240x= 1800+ 150x

90x= 1800

x=20

A: The fast horse can catch up with the slow horse in 20 days.

Six: (1) Solve the first encounter when crossing X:

350x+250x=400

600 times =2/3

(2) Meet again when the solution passes through X:

350x+250x=400×2

600 times

=800

=4/3

Seven: A swimming pool sells summer membership cards from June to August every year, and each 80 yuan is for personal use only. If you buy a ticket, you can buy a ticket at 1 yuan. If you don't buy a ticket, you can buy a 3 yuan. Please answer: [1] Under what circumstances, buying a membership card is as rich as not buying a membership card. [2] Under what circumstances is it more cost-effective to buy a membership card than not to buy it? [3] Under what circumstances, it is more cost-effective not to buy a membership card than to buy one? 6,7,8 * * three months, that is, 30+3 1+3 1=92 days [1]. Suppose that the money paid by members and non-members when they go to A is the same-then: the money paid by members is equal to: 80+ 1A, that is: 3A.

80+A=3A, the solution is A=40 times [1] Go swimming for 40 times (including 40 times). Buying a membership card is the same as not buying a membership card. In this case, the answers [2] and [3] are obvious: [2] It's more cost-effective to buy a membership card than not to go swimming for 465 or 438+0 times in June and August. [3] When you go swimming for 39 times or less from June to August, it is more cost-effective not to buy a membership card than to buy one.

Eight: Solution: Let it be divided into right angles by X from 3 o'clock. (The difference between the hour hand and the minute hand at right angles is 15. )

┃x-( 15+(5/60)x)┃= 15

Then x-(15+(5/60) x) =+15 or = x-(15+(5/60) x) =-15.

Get X=0 or X=360/ 1 1.

X=0 shed

X=360/ 1 1

We start at 3 o'clock and divide it into right angles through X (the difference between the hour hand and the minute hand is 30 points)

┃X-( 15+(5/60)X)┃=30

Then X-( 15+(5/60)X)=+30 or =X-( 15+(5/60)X)=-30.

X=- 180/ 1 1 or x = 540/1.

X=- 180/ 1 1 shed

X=540/ 1 1

Let's start at 3 o'clock and overlap x points. (Coincidence means that the difference between the hour hand and the minute hand is 0 and equal. )