A+B = 3 A-B = 2 A = 5/2 B = 1/2 A/B = 5

There are 1 red balls and 2 white balls in the pocket. What is the probability of finding two balls from them after mixing evenly?

The probability of meeting two is red and white, so the probability of meeting one red and one white is 50%

3 Solve the equation with the formula: x 2+8x- 1 = 0.

X =-8 64-4 *1* (1)/2 *1x1=-4+radical 17 X2=-4- radical 17.

4 The parabola y = 1/2x 2+2x-6 is known. First convert it into the form of y = a (x-h) 2+k, and then answer the following questions.

(1) Find the opening direction, vertex coordinates and symmetry axis of the parabola; (2) Find the coordinates of the intersection of parabola and X axis;

(3) What is the value of X, and Y decreases with the increase of X?

Y= 1/2(X+2)^2-8

(1) Vertex coordinate of upward opening (-2 -8) Symmetry axis X=-2

(2) The coordinates intersecting with the X axis are to be found.

The solution of1/2x2+2x-6 = 0x2+4x-12 = 0 (x-2) (x+6) = 0 (-60) (20).

The flowerpot is used in the garden to cultivate some kind of flower seedlings. Through experiments, it is found that the profit per pot is related to the number of plants per pot. When 3 plants are planted in each pot, the average profit per plant is 3 yuan; Under the same cultivation conditions, each pot increases 1 plant, and the average profit per plant decreases by 0.5 yuan. How many plants should be added to each pot to make the profit per pot reach 10 yuan?

Three plants per pot, one pot is profitable for 9 yuan.

Each pot increases 1 plant, the average profit per plant decreases by 0.5 yuan, and the increase of X plants decreases by 0.5X yuan.

The profit per pot is (3-0.5X)(X+3) yuan.

(3-0.5X)(X+3)= 10

X= 1 or 2

Each pot contains 4 plants 1 plant, and the unit price is 2.5 yuan *** 10 yuan.

Two plants in each pot make five plants, and the unit price is 2 yuan *** 10 yuan.