Math Problems Continue Again, Continue to Math Problems

Solution: Because the original defense process has two roots.

So the discriminant formula is greater than 0

k^2-4(k^2+n)=-3k^2-4n>0n<-3k^2/4<0

According to Veda's theorem.

x1+x2=k

x1x2=k^2+n

Because. 2x1+x2) 2-8(2x1+x2)+15=0so. x1+k)^2-8(x1+k)+15=0x1+k-3)(x1+k-5)=0

x1+k=3 or x1+k=5

When n=-3.

x1=3-k

Bring back the original equation.

Get an equation about k and solve k.

x 2-kx+k 2+n=0 has two unequal real roots, then there are k 2-4(k 2+n)>0

Get n<-3k 2 4

So n<0

x1+x2=k

2x1+x2) 2-8(2x1+x2)+15=0 can be written as (x1+k) 2-8(x1+k)+15=0

The solution yields x1+k=3 or 5

x1 = 3-k or x1 = 5-k

The conclusion in the first question is deformed: k 2 < -4n 3

When n=-3, k 2<4

2x1x2=k^2-3

I had a cold, and the third question card was asked. sorry!

Solution: Let y=4 x, then 2(16 x)- 5(4 x) +2=0 is 2y 2-5y+2=0

2y-1)(y-2)=0

then y=1 2, or y=2

When y=1 2, 4 x=1 2, solved with logarithms, x=lg(1 2) lg4, when y=2, 4 x=2, solved with logarithms, x=lg(2) lg4,

Let 4 x be t, you can become 2t 2-5t + 2 = 0, a quadratic equation.

4 x is set to y, and the equation becomes 2y square, -5y+2=0, and the solution is y=2 or 1 2, then x=1 2 or -1 2

ps: How do you want people to give ...... to the process, this question

Set y 4 x

The original equation is 2y 2-5y+2=0

Solve y 1 2 or y 2

So x 1 2 or x 1 2

1), Let the swimmer be x, and the non-swimmer be yx=20 100*y

y-x=32

Solution: Eq. 1 plus Eq. 2 equals:

x+y-x=

y=32 people.

x=person2), next day see: =60*(1+page; (Note: This is the total number of pages counted from 60 pages on the first day + 15 pages on the second day).

The next day I read: =60*pages;

Day 3 read: =15 pages.

3), =20 (pcs.)

4), Winter melon=160 (pcs.)

Pumpkin = 800 * (the same as the first problem, if you can't calculate, you can solve the equation) or more

Question 1: If the number of people who can't swim is x, then the number of people who can swim is, and there are: If the solution is x=40, then the number of people who can swim is human.

Question 2: The number of pages read on the second day is 60*:; On the third day, the number of pages of the book is 15*Question 3: A total of x balloons have been prepared; Red has; Yellow has;

Yes Solution x=100 i.e. there are a total of 100 fourth questions: let there be x winter melons; Pumpkins have;

Yes x=800 and 640 pumpkins.

Be fg to O

e, b about fg symmetry (fold).

eo=bo, so ef=fb

FBO congruent ΔFOE

So angular foe = angular fob

Angular foe = angular gob

So angular foe = 90°

be=13 with similar δ

Find fo=13 30

Again, go=26 30

On the same circular track, both of them run in a clockwise direction and meet every 12 minutes, if the speed of the two people remains the same, one of them will run in a counterclockwise direction and meet every 4 minutes, and each of them will run a lap, how many minutes will it take.

Solution: The velocity difference is 1 12

Speed and 1 4

So the speed of a fast person: (1 12 + 1 4) 2 = 1 6 The speed of a slow person: (1 4-1 12) 2 = 1 12 The fast person needs to: 1 1 6 = 6 minutes.

Slow needs: 1 1 12 = 12 minutes.

I'm a teacher, thank you.

If the length of the whole journey is s, then the speed of the two people is v1+v2=s 4, and the speed difference v1-v2=s is 12

Add the two formulas. 2v1=s/4+s/12=s/3s/v1=6

Subtract the two formulas. 2v2=s/4-s/12=s/6s/v2=12

It takes 6 minutes for one person and 12 minutes for the other.

The fast one runs 1 x lap per minute, and the slow one runs 1 y lap, so 1 x-1 y = 1 12; 1 x + 1 y = 1 4, the solution gives x = 6, y = 12

Let the faster ones take x minutes and the slower ones take y minutes, then there is:

1/x+1/y=1/4

1/x-1/y=1/12

Treat 1 x and 1 y as a whole, respectively.

1 x = 1 6 i.e. x = 6

1 y=1 12 i.e. y=12

6 meters (6 people 6 hours) rot = 1 6 (meters per person per hour) dust search.

100 meters (100 hours 1 6 meters per person per little brother preparation) = 6 people.

6 pcs, with an average of 1 person digging 1 meter every 1 hour.

5.For example, if you choose c, y=x 3, y=x 4 and x=0 will meet the conditions in the question, y=x 3 in x=0 will be the inflection point, and y=x 4 will be the minimum in x=0.

6.I choose A

f'(x) >0 illustrates a monotonic increase, f''(x) <0 indicates convex.

7.I choose B

f(0)=e^0=1=lim(a+x)=a，a=1.

÷8=1／8

5 8 = 5 8 kg.

A: On average, each person gets one-eighth of 5 kilograms, and each person gets five eighths of kilograms.

Centimeter = 10 km.

10 15 = 150 km.

A: The actual distance is about 150 kilometers.

3. Width: 10 2 = 5 cm.

Length: 3 + 5 = 8 cm.

5 8 = 40 square centimeters.

A: Originally, the area of the rectangle was 40 square centimeters.

I hope it can help you, I wish you progress in learning, please continue to ask if you don't understand

1. Each person gets 5 kg of 1 8. 5 8 kg per person.

cm=150000m=150km。

3. If the length is reduced by 2 and the area is reduced by 10, then the width is 5

If the width plus 3 and the length and width are equal, then the length is 8

The area is 5*8=40 square centimeters.