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Math problems in the second day of last semester
1, function y=-6x image l? Translate 5 units up to get a straight line l? The equation for L2 is

Y=-6x+5, and its intersection with the coordinate axis is (0,5) (5/6,0).

The area of the triangle is 1/2*5*5/6=25/ 12.

2

x-5y+ 17=20 ①

3x- 10y-20=- 16 ②

Multiply ① by 2.

2X- 10y+34=40 ③

③-②

-x+54=56

x=-2

Substitute (1)

y=- 1

3x+5y=2 1 ①

2x-3y=-5 ②

② Multiply by 3/2.

3x-9x/2=- 15/2 ③

①-③ Acquisition

19y/2=57/2

y=3

Substitute (1)

X=2

3.8W energy-saving lamp price X yuan, 24W energy-saving lamp price Y yuan.

Then 4x+3y=29, 2x+2y= 17.

The solution is x=3.5 and y=5.

8W energy-saving lamp price in 3.5 yuan, 24W energy-saving lamp price in 5 yuan.

China can save about 5000 * 2.3/850 = 65.438+35 billion yuan of electricity a year.

Carbon dioxide emission reduction is about 5000 * 43.5/850 = 2.559 million yuan.