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(1) If there is an 80cm long iron wire, which is used to form a rectangle, and the length of the rectangle is 10cm more than the width, what is the length and width of the rectangle? What is the area of the rectangle? (2) If the wire is used to form a square, what is the side length and area of the square? (3) If this wire is used to form a circle, what is the radius of the circle? What is the area What conjecture can you get if you use 100cm and 120cm iron wire respectively according to the requirements of (1), (2) and (3)?
one
x+y=40
x-y=10
x=25
y=15
s=15*25=375
two
4x=80
x=20
s=400
three
2πr=80
r=40/π
s=πr^2=1600/π=510
Conjecture: the circle has the largest area when the circumference is equal
Please fill in the blanks in math for grade five, thank you! (19:16:17:35)
A cuboid is 2 meters long. Cut it into two small cuboids. The surface area is increased by 30 square decimeters. The cuboid's volume is [&# 160; &# 160; &# 160;] cubic meters
The surface area increased by 30 square decimeters
Bottom area = 30 △ 2 = 15 square decimeters
Volume = 15 × 2 = 30 cubic decimeter = 0.03 cubic meter
A: the volume is 0.03 cubic meters
The average number of a and B is 60, the average number of a, B and C is 65, what is the number of C?
65×3-60×2=75
In linear algebra, what is the relationship between vector space and the matrix, determinant and linear equations in the previous chapters?
Matrix is a tool to describe the linear transformation of vector space, and can also be regarded as an ordered set of vector groups
Determinant is mainly used to calculate the rank of matrix. Linear equations can solve the problem of linear representation
A, B and C process 940 parts at the same time. It takes 3, 4 and 5 minutes to process one a, B and C. how many parts did B process when it was finished?
The number ratio is 1 / 3:1 / 4:1 / 5
940×1/4÷(1/3+1/4+1/5)=300
A: Party B has processed 300
What is 23 - (x + 3.5x) = 7x equal to
23-(x+3.5x)=7x
7x+4.5x=23
x=2
There are two granaries A and B. the original tonnage of grain stored in warehouse A is five seventh of that in warehouse B. If 6 tons of grain are transferred from warehouse B to warehouse A, the tonnage of grain stored in warehouse A is the same as that in warehouse B
Four fifths, how many tons of each?
If B stores x tons of grain, then a stores 5x / 7 tons of grain
X-6=4(X-6)/5
Solution x = 6,5x / 7 = 30 / 7
The original stock of B is 6 tons, and that of a is 30 / 7 tons
Why 7x + 4x = 3x?
The square of 3x - [the square of 7x - (4x-3) - 2x]
=3x²-(7x-4x+3-2x²)
=3x²-7x+4x-3+2x²
=5x²-3x-3
It's - 7x + 4x = - 3x
Pay attention to the symbol in front of it
How to calculate 25 + 75-25 + 75 simply
25+75-25+75=25+(100-25)-25+(50+25)=150
Suppose that the number of terms of an equal ratio sequence is even, the sum of all terms is four times of the sum of its even terms, and the product of the first three terms is 64
Even term
First term AQ, common ratio Q ^ 2
Sum = AQ (1-Q ^ 2n) / (1-Q ^ 2)
Why is the common ratio Q ^ 2
Is the even term Q ^ 2
0
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