Summary and Reflection on unit 2 of mathematics evaluation manual for Grade 7 (Suke Edition) answers to lesson 2

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Mathematics Evaluation Handbook (Suke Edition) Grade 7 Volume 2 p23 question 7

In class, we try to calculate. First, the m power of a multiplied by the n power of a multiplied by the P power of a = a multiplied by A. second, the m power of a multiplied by the n power of a multiplied by the P power of a = the M + N + P power of a

It is known that A-B = 7. The square of a minus the square of B = 56?
fast

a-b=7.a^2-b^2=56
a^2-b^2=(a-b)(a+b)=56
a+b=8
ab=[(a+b)^2-(a-b)^2]/4=(64-49)/4=15/4
Or a = 15 / 2, B = 1 / 2

8.56 times 10 square - 2.1 times 10 cubic
The answer is science and technology

8.56 * 10 square - 2.1 * 10 cubic
=10^2(8.56-21)
=-12.44*10^2
=-1.244*10^3

The side area of a cylinder is 12.56 square meters, the bottom radius is 4 decimeters, how many decimeters is its height?

12.56 △ 3.14 × 4 × 2, = 12.56 △ 25.12, = 0.5 (decimeter); a: its height is 0.5 decimeter

The side area of a cylinder is 12.56 square meters, the bottom radius is 2 decimeters, and its height. Please

2 decimeters = 0.2 meters
The circumference of the bottom circle is 0.2 times 2 times π = 0.4 π
When the cylinder is opened, it can be seen as a rectangle with a length of 0.4 π and an area of 12.56
So height is width, which is 12.56 divided by 0.4, which is 31.4 meters

The congeners are: (a + b) 2 − 32 (a + b) − 14 (a + b) 2 + (− 2) 3 (a + b)

The original formula = (a + b) 2-32 (a + b) - 14 (a + b) 2-8 (a + b) = 34 (a + b) 2-192 (a + b)

The cube of x plus x square plus x plus 1 is equal to 0 Add to the power of x2019

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What is number pair

Number pairs are equivalent to coordinates, so it's easy to judge the position of a certain place. In fact, there are number pairs everywhere in our life. But who invented number pairs by paying attention to life? Number pairs were invented by Descartes. Once, when he was sick, lying on the bed, he found a spider in the corner of the wall. Descartes took the position of spider as the beginning (0,0), I think number pairs can not only represent two-dimensional space (length, width), but also three-dimensional space (length, width, height) or four-dimensional space (length, width, height, time). All the points in the world can be represented by number pairs, So the number of pairs will bring great convenience to our life
For example: Beijing: north latitude (39 ° 57 ′) east longitude (116 ° 28 ′)

When a number pair is used to represent a position, it usually represents the first number What's the number ．

When a number pair is used to represent a position, it usually represents a column first and then a row

Summary and Reflection on unit 2 of mathematics evaluation manual for Grade 7 (Suke Edition) answers to lesson 2