Very urgent! Easy math problems! 35

Solution: Original formula = 1 2-1 2 * (2-double root number 2 + 1) =1 2-(1-root number 2 + 1 2) = 1 2-1 + root number 2-1 2 = root number 2-1

If the wholesale price of fountain pens is x and the wholesale price of erasers is y, then their retail prices are x+ and y+30*(2*(x+.)

2x+y= (i)

30*(3x+2*y)=

3x+2y= (ii)

i)*2-(ii)

x=substitution(i)=》y=

Therefore, the wholesale price of fountain pens is yuan, and the wholesale price of erasers is yuan.

From the first sentence, I know that if you buy 2 pens and 1 eraser for all students, each student will spend 1 yuan, that is, 2 pens and 1 eraser is 1 yuan.

Let the ** of the pen be x and the eraser be y

2x+y=1

From the following conditions, it can be seen that the ** of 3 pens and 2 erasers at the wholesale price is the ** of the fountain pen and the ** of the eraser is at the wholesale price, and the ** of the eraser is , in the column equation 3 (

Just solve these two equations, you can do this yourself.

.5+6*

6-5= so dollars per kilometer.

So 5+

The size of the shoe with a size 7 is:

The size of the shoes marked M is:

According to: the root number is non-negative, and the system of equations is solved.

1: x+y-8 is greater than or equal to 0

8-x+y is greater than or equal to 0

Get: x+y=8

2.Because left = right.

3x-y-a=0 x-2y+a+3=0

These three systems of equations are calculated that x and y = 3 or 5a = 4 hook 3 strand 4 strings 5 respectively and are right triangles. The right-angled sides are 3 and 4.

Area=(3*4) 2=6

Non-negative x y 8=8 x y=0 8=x+y3x y a=0 in the root number

x－2y＋a＋3=0

x=,a=4

Obviously can, area 6

1.Write the trillions of conductors of f(x), g(x).

f '（x）=x^2-(a+1)x-4(a+5)g ' x) =5/x+ax-1

Let the derivatives of f(x) and g(x) be zero.

Right f'(x), x=-4 or x=a+5

To g'x), the sail rough rent ax 2-x+5=0 if x=-4, a=-9 stool noisy 16

If x=a+5, a=0, -4, -6

y is equal to two-thirds x is equal to minus one.