Simple math problems, solve 1 simple math problems urgently

Solution: (1) half a minute = 30 seconds, 30-12 = 18 (seconds), 18 6 = 108 (meters);

a: 60 + 108 = 168 (m) b: 55 + 108 = 163 (m) c: 50 + 108 = 158 (m);

A: After half a minute, they were all 5 meters apart

2) 1 minute = 60 seconds, 60-30 = 30 (seconds), 50-30 = 20 (seconds), 30-20 = 10 (seconds);

a: 168 + 20 5 + 10 6 = 328 (m);

b: 163 + 30 6 = 343 (m);

c: 158 + 30 6 = 338 (m);

A: B is 5 meters before C and C is 10 meters before A

1) Half a minute = 30 seconds, 30-12 = 18, 18 6 = 108a: 60 + 108 = 168, b: 55 + 108 = 163, c: 50 + 108 = 158

A: After half a minute, they were all 5 meters apart

2) 1 minute = 60, 60-30 = 30, 50-30 = 20, 30-20 = 10;

a：168+20×5+10×6=328；

b：163+30×6=343；

c：158+30×6=338；

A: B is 5 meters before C and C is 10 meters before A

It's simple.

c The second function, to simplify a bit.

y=(x-3)(x+3) (x-3)(x-4)When x is not equal to 3, y=(x+3) (x-4) is the same as the first function, so the first function has more value than the second function when x=3, i.e., p>=q

Choose c because x is not equal to 4 in the first function, and the second function is reduced to (x-3)*(x+3) (x-4)*(x-3)=

x+3) (x-4) is the same as the first one, but the second x cannot be 3, so the value of the first function has an extra x equal to 3, so q is a true subset of p.

Why do fractional equations have to be used? It's easier to calculate directly: 40*[15 (40-15)]=24 seconds.

Using the equation, the equivalence relationship is: A 15 seconds line B 15 seconds line of the whole process (that is, unit 1), the landlord himself column formula!

This should be the mathematics of Haidian in 2009.

We just did it.

1.Necessary but not sufficient conditions.

Solution: Let a=1, b=4 when two straight lines are collinear!

Actually, it's good that you pay attention to this.

However, if the slope does not exist, i.e., a=0, then b cannot be parallel no matter what value is taken, because the slope of the straight line 2 must exist, and it makes no sense to consider it in this problem! However, if the slope of straight line 2 may not exist, i.e., the position of b is before the coefficient of y.

Then it is necessary to consider whether K exists or not!

This is a fill-in-the-blank question.

The main method can be to write a few conjectures (if you can continue to use mathematical induction to prove the correct solution: (but this method is not suitable for choice and fill-in-the-blank questions)!

sn=1-nan

sn=1-n(sn-sn-1)

(n+1)sn-nsn-1=1

nsn-1-(n-1)sn-2=1

3s2-2s1=1

stacked. n+1)sn-2s1=n-1

s1=a1=1-a1

a1=1/2

n+1)sn=n

sn=n/(n+1)

Let's take an example of a positive number, which is more convenient to explain.

Actually, (a m) n = a (m*n).

3x^2 + 13x - 10 = 0

x+5）（3x-2）=0

x= -5 x=2/3

Exact values means exact values. Complete!

I don't know what exact values mean, though.

Factoring.

3x-2）*（x+5）=0

x=2 3 or x=-5

Solution: 1) f(-1)=-1-a 2=-5, a 2=4, a>0, a=2,2) f(x)=x+2 x, the domain of definition is (- 0) (0,+ with respect to origin symmetry, f(-x)=-x-2 x=-(x+2 x)=-f(x), i.e., f(-x)+f(x)=0

f(x)=x+2 x is the odd function,