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2 math problems = w= A cylindrical wood is 10 meters long. After it is cut into two cylinders, the surface area increases by 0.4 square meters. What is the volume of the original wood? 2. A cone-shaped wheat pile with a bottom radius of 2 meters and 8 meters. If the wheat is put into a cylindrical grain bin with a height of 4 meters and is just full, how many square meters is the bottom area of the cylinder?
(1) If the radius of the bottom is r, the original volume is 10 π R & sup2; = 5x2 π R & sup2; = 5x0.4 = 2 (M3) (2) cone volume is v = 1 / 3xsxh = 1 / 3x π R & sup2; X1.8 = 2.4 π (M3), so the area of the cylindrical bottom is v / h = 2.4 π / 4 = 0.6 π
Two calculation problems of binary linear equations in grade one of junior high school
1.3x+4y=16
5x-6y=33
2.4(x-y-1)=3(1-y)-2
2 / x + 3 / y = 2
(must write the process)
Substitution method
1. Substitution method 3x + 4Y = 16 → x = (16-4y) / 3, substituting x into 5x-6y = 33 to get 5 (16-4y) / 3-6y = 33, and then substituting x = (16-4y) / 3 to get x = 6. Elimination method can also be used to multiply all the coefficients of the first equation by 5, and all the coefficients of the second equation by 3 to get 15x + 20Y = 8015x-18y = 99
Please do me a favor! 2 calculation problems and 2 application problems!
1. 1.8 × 1 / 9 =?
2. 3 / 4 × 5 / 8 + 0.75 × 3 / 8 - (← minus sign) 1 × 3 / 4
3. Xiaohong's walk from home to the supermarket has been reduced from 10 minutes to 8 minutes now. How much faster has Xiaohong been?
4. A and B set out at the same time from two places 10 kilometers away from the east to the West. A walked 3 kilometers per hour, B walked 2 kilometers per hour, and they met a few hours later? If a took a dog and started at the same time with a, the dog ran to B at the speed of 5 kilometers per hour, and when it met B, it turned back to a; when it met a, it turned back to B, and it didn't stop until a and B met, How many kilometers did the dog run?
1、0.2
2、0
3. The speed increases from 1 / 10 to 1 / 8 per minute, so it increases by (1 / 8) / (1 / 10) × 100% - 1 = 25%
4. It takes 10 / (3 + 2) = 2 (hours) for two people to meet
So the dog ran for 2 hours, and the dog ran for 5x2 = 10 (km)
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