Math Exam Focus! Urgent!!! 6th grade .

You can ask the teacher, because some formulas on the Internet are difficult to write.

Math: Straight line ray segments.

1.Solid shapes: Geometry where parts are not in the same plane become solid shapes. Common three-dimensional shapes can be divided into cylinders, cones, spheres, and tables.

2.Plane shape: The geometry of each part in the same plane becomes a plane shape, such as: rectangle, square, circle, trapezoid.

3.For some three-dimensional figures, they are often transformed into flat figures for study

1) Three views: Represent three-dimensional graphics with plane graphics seen from different directions (such as front, left, top) (these three types of plane graphics are called: main view, left view, top view 0

2) Plane figure: Cut a three-dimensional figure along one of its sides to become a plane figure, and this plane figure is called a three-dimensional figure diagram.

4.Straight lines, rays, line segments.

10 Straight Line Axiom: To fix a wooden strip on the wall, Xiao Ming said that only two nails are needed. The mathematics used in this is that two points determine a straight line.

2) There are two positional relationships between a point and a straight line (or ray, line segment).

a.The point is outside the line (or ray, line segment);

b.The point is on a straight line (or ray, line segment).

3) Line segment axiom: between two points, the line segment is the shortest.

4) The focus of the line segment: If AB=6 and AC=3 are known, then CB=3, and the point C is called the midpoint of the line segment AB. Map.

This data is ** on the map, and the final result is subject to the latest data on the map.

1. False. 2. False, if all are qualified, the pass rate is 100%.

3. Wrong, the quality of the brine is 105, so the salt accounts for the brine.

4, right.

1. Wrong because the unit cannot be added after the percentage.

2. The pass rate is 100, so it is also wrong.

3. Do the math yourself if dividing 5 by 105 is 5 percent.

4. That's right.

Judge right from wrong. 1. A one-meter-long rope has used 30% of the remaining 70% of the meters. (False) 2. Master Li processed 90 parts, all of which were qualified, and the pass rate was 90%.

3. Dissolve 5 grams of salt in 100 grams of water, and salt accounts for 5% of the brine. 4. Divide the five-meter-long iron wire into 10 equal parts, each accounting for 10% of it. Right).

Let them use the time x

15x+18x+20x=1590

x = 30 (minutes).

A: 15*30=450 (pcs).

B: 18*30=540 (pcs).

C: 20*30=600 (pcs).

1590 divided by (15 + 18 + 20) = 30 (pieces) A: 30 * 15 = 450 (pieces).

B: 30*18=540 (pcs).

C: 30*20=600 (pcs).

They do it together every minute: 15 + 18 + 20 = 53;

They do it together: 1590 53 = 30 minutes to do it;

Separately assigned: A 15 * 30;B 18*30;C 20*30

An absolute value of zero is only possible if it is internally zero, so x=3