1

You did the first question yourself.

(2)

Solution: let the analytical formula of linear function be y=kx+b,

The image passes through points (40, 600) and (50, 900)

600=40k+b

900=50k+b

Get a solution

k=30

b=？ 600

The analytical formula is y=30x-600.

When y=0, x=20, that is, the weight does not exceed 20 kg.

2

y=-2x+4，

Let x = 0 and y = 4.

Let y = 0, -2x+4 = 0 and x = 2.

So a is (2,0) and b is (0,4).

Because in the triangle AOB, AO is the bottom and BO is high.

So the area =|2|*|4|/2=4.

three

(1) according to the image, the functional relationship between y and x can be set as: y=kx+b, points (10,50) and (50, 150) are substituted, and {10k+b = 5050k+.

Solution: k= 52, b=25, so y= 52x+25.

(2) When x=30, y = 52× 30+25 = 100. That is to say, the water tank has 100 liter of water in 30 minutes.

four

five

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