Mathematics in the second year of junior high school seeks the process and result, and mathematics i

1) and (2), when x is greater than or equal to 0, the situation is met.

3) When m and x are in the same direction, the requirements are met, that is, x and m are greater than or equal to 0 at the same time, or x and m are less than or equal to 0 at the same time.

2.According to the title, it can be found that a=3 7>0, so as the independent variable increases, the value of the function increases.

Note: This kind of question can be drawn directly and can be seen at a glance. I have summarized a rule before: call 4231y=ax+b, a>0, b>0, without passing through the fourth quadrant.

a>0, b<0, do not pass through the second quadrant.

a<0, b>0, do not pass through the third quadrant.

a<0, b<0, do not pass through the first quadrant.

Hello. Question 1. Be. Be.

It's not that the m-value uncertainty range makes it impossible to know how to change.

Question 2. Bring the coordinate points into the equation.

2=-7a+5

a=3 7 so the function is y=3 7x+5 is a proportional function, so the value is increasing.

1) In any case, y increases as x increases.

2) Because a2+1 1, y increases with x in any case.

3) When m > 0, y increases with the increase of x, when m=0 is, y = root number 5, and when m < 0, y decreases with the increase of x.

After the point p(-7,2), that is, when x=-7, y=2, 2= -7a+5, the solution is a=3 7,a>0, and y decreases with the increase of x.

Increase, increase, m >0 increase, and vice versa. Enlarge, bring the coordinates in, a = 3 7>0

ae=t cf=2t

PG is equal to AE parallel tangent.

If AEFG is rhomboid, AE=AF is required, i.e., t=30-2t, t=10 sec.

The triangle EFG is a right angle, and the triangle can only be an angle, EFG = 90 degrees, that is, the EF is parallel to BC

Then we can see that the triangle AEF and the triangle ABC are similar triangles, so AE AB=AF AC

5 15 = (30-2t) 30 t = that is, at this time f is just the midpoint of ac and e is just the midpoint of ab, so eg = 15cm

1、ae=t，cf=2t

fg∥ae，fg=ae

2. AF=AE is a diamond.

Then t=30-2t

t=103、∵∠abc=90°，∠acb=30°

ab=1/2ac=15

EF BC, then EFG=90°

Then EFG is a right triangle.

af/ac=ae/ab

30-2t）/30=t/15

2t=30-2t

4t=30t=

Here's how to answer it.

In this problem, the length of AB is 1, then the coordinates of point B are (0,1) or (0,-1), so the coordinate points of point C are four points in total, and the length from point C to AB is [1-(1 2) 2]= 3 2, so the coordinates of point C are (3 2,1 2) or (3 2,-1 2) or (- 3 2,1 2) or (- 3 2,-1 2).

I really can't draw a picture, I hope this sketch can deepen your understanding, four points If you don't understand, please continue to ask!

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The root of the second is numbered three, and the root of the second is one.

There are 4 answers (minus half root number 3, half of the root number) (half of the root number 3, minus half of the root number) (minus half of the root number, 3 minus half of the root number) (half of the root number 3, half of the root).

Draw a diagram and make an auxiliary line from point c to the y-axis according to the Pythagorean reason, and write out the points of the 4 intervals.

∵ x1+x2=-(2m+1)

x1*x2=m^2+1

x1^2+x2^2=(x1+x2)²-2x1x2=[-(2m+1)]²2(m^2+1)

2m^2+4m-1

x1^2+x2^2=2m^2+4m-1=152m^2+4m-16=0

m^2+2m-8=0

m+4)(m-2)=0

The solution yields m=-4, or m=2

When m=-4, the original equation is x 2-7x+17=0, 0, no solution, rounded;

When m=2, the original equation is x 2 + 5x + 5 = 0 , 0, m = 2

The first question is correct, and the second question, when the cost is 20 million yuan, it is not y=2000, but yx=2000

Y represents the number of units produced, i.e., -x squared 2+65x=2000, calculated as x=50 or 80, and it is verified that 80 is not in line with the topic, so x=50, y=40;

3. z=-a+90;

When Z=25, A=65

Profit = 25 (65-40) = 625