Math Answer 2, Ask Math Answer 2.

Solution: (1) f'(x) = 3mx 2+4nx-12, from the question -2, 2 is f'(x)=0, 2+2=-(4n 3m), (2)*2=-12 3m, n=0, m=1; At this point, f(x)=x3-12x,f'(x)=3x^2-12

2) At x = 1, f'(1) =-9, i.e., k=-9, the slope of the tangent exists, that is, assuming that the tangent equation is, the crossing point y=kx+b passing point a(1,-11), k+b=-11, so b=-2, and the tangent equation is y=-9x-2

Solution: (1) From the meaning of the question: f'The solution set of (x)=3mx2+4nx-12 0 is (-2,2), so -2 and 2 are the roots of the equation 3mx2+4nx-12=0, (2 points).

From Veda's theorem, we know that 0=-4n 3m, -4=-12 3m, i.e., m=1, n=0 (4 points).

2）∵f（x）=x3-12x，∴f'（x）=3x2-12，∵f（1）=13-12•1=-11

When a is the tangent point, the slope of the tangent is k=f'(1)=3-12=-9, and the tangent is y+11=-9(x-1), that is, 9x+y+2=0;(6 points).

When a is not a tangent point, let the tangent point be p(x0,f(x0)), then the slope of the tangent is k=f'(x0)=3x02-12, and the tangent equation is y-f(x0)=f'(x0)(x-x0), i.e., y=3(x02-4)x-2x03

Because the crossing point a(1,-11),-11=3(x02-4)-2x03, 2x03-3x02+1=0,(x0-1)2(2x0+1)=0,x0=1 or x0=-1 2, and x0=1 is the point a, that is, the other tangent point is p(-1 2, 47 8 ), k=f (-1 2 )=3 1 4 -12=-45 4 , and the tangent equation is y+11=-45 4 (x-1), that is, 45x+4y-1=0 (8 points).

So, the tangent of the crossing point a(1,-11) is 9x+y+2=0 or 45x+4y-1=0

(1) For a job, it takes 20 hours for A to do alone, B to do it alone for 2 times more than 4, C to do it alone for 1/2 hours more than 2 hours for A, if A and B work together for 10 hours and C does it alone, how many hours does it take for C to complete?

B alone do the time is.

20 2 4 44 (hours).

C alone does the time is.

20 1/2 2 12 (hours).

The cooperation between A and B will be completed in 10 hours.

1/20 1/44) 10 8/11 The rest is done by C alone to complete the need.

1 8/11) 1/12 36/11 (hour) (2) If a product is ready to be sold at a discount due to the change of seasons, if the discount ** will be 25 yuan according to the price, and the discount ** will earn 20 yuan according to the price, Q: How much is the price of this product?

Pricing is: (20 25) (95 75) 225 (yuan).

Hello, I am inquiring for you here, please wait a while, I will reply to you immediately Hello, I have understood the problem, I need a little time to reply to the content, thank you for your understanding Hello, because it is pure hand calculation, it takes a little time, I hope you can wait for me to ask a question. Good good.

Okay. <>

You can do the math yourself

, are the two real roots of the equation x -3x-5=0 so -3 -5=0

Similarly, =3 +5

So the original formula = 3 +5 + 2 (3 + 5)-3

By the Vedic theorem.

So the original = 24

From the equation we know a+b=3. So a=3-b, substitute the required and sort out 3 (3-3b+b 2).

From the original formula we know b 2-3b = 5

So the requirement is equal to 24

Dale Ta = 0, get 36m 2-4m (m+8) > = 0

m(m-1)>=0Because m is not equal to 0, m>=1 or m<0

(1) When m=0, the equation is 8=0, which is not true.

2) When m is not 0, the equation is a quadratic equation. The discriminant formula for the root (-6m) is greater than or equal to 0Solve the inequality and get m less than or equal to 1

It's pretty simple.

To have a real root, you must first have o

mx²-6mx+m+8=0

(-6m)²-4m(m+8)

32m²-32m

0 within 32m -32m

m 0 or capacity m 1

In summary, m o always has a real root.

The circular equation is (x-2) +y-2) =1

If the reflected ray is tangent to the circle, then the line where the incident ray is located is tangent to the symmetrical circle with respect to the x-axis, and the symmetrical circle equation is (x-2) +y+2) =1, that is, the tangent distance of (-3,3) is found for the center of the symmetrical circle (2,-2), and the distance of the circle is radius 1, and the straight line is (y-3)=k(x+3).

That is, kx-y+3k+3=0

The distance of the straight line from (2,-2) d= 2k+2+3k+3 (k+1)=1

k²+1=25k²+50k+25

12k²+25k+12=0

k = -4 3 or k = -3 4

y=-4 3x-1 or y=-3 4x+3 4

Let y=k(x-x0)+y0, and substituting y=k(x+1)+2 at point a, and use the distance formula from point to line, the distance formula from p1 to that line = the distance formula from p2 to that line, and get that k has only one value of -1/3, and the result is y=-1 3(x+1)+2

Solution: (1) log2 (in the lower right corner) 15=LG15 LG2=(LG5+LG3) LG2=(1-LG2+LG3) LG2=(1-a+b) A

2) Original = 25 4 + 4 root number under the root number 2 + root number 2 + 100 9 + 9 = 407 18 + 4 root number 2

I also don't type those math symbols, I don't know if you can read them)

This is the question of our winter vacation homework. Which school are you from...

log215=lg15/lg2=（lg3+lg5）/lg2=（lg3+1-1g2）/lg2

Substitute A and B in it.

The second primitive formula is equal to 5 2 + 16 root number 2 + negative quadratic 9 = 5 2 + 16 root number 2 + 100... I don't really understand what the cube of 2 2 means...

The number of indoor parking spaces is X, and the number of outdoor parking spaces is Y

5000x+1000y=150000

y=150-5x

150-5x>=2x, 150-5x<=20<=x<=150/7

x1=20,x2=21

y1=50,y2=45

There are only two numbers in binary: 0 and 1 3 in decimal is equal to 11 How to convert a binary number into a decimal number: 11101 (2) = 24 + 23 + 22 + 20 = 16 + 8 + 4 + 1 = 29 (10) How to convert a decimal number into a binary number:

10 (10) = 23 + 21 = 1010 (2) The number after 2 is an exponent, and somehow it has such an effect.