For a ring, the circumference of the inner circle is 31.4cm and the circumference of the outer circle is 94.2cm. What is the area of the ring?

For a ring, the circumference of the inner circle is 31.4cm and the circumference of the outer circle is 94.2cm. What is the area of the ring?

Inner circle radius 31.4 △ 2 △ 3.14 = 5
Outer circle radius 94.2 △ 2 △ 3.14 = 15
3.14×15×15-3.14×5×5=628
A: the area of the ring is 628 square centimeters

The perimeter of the outer circle of a ring is 25.12cm, and the perimeter of the inner circle is 18.84cm

Circle area formula: π times (the square of the radius of the big circle minus the square of the radius of the circle)
The formula of the area of the peripheral field is the square of π R
π is about 3.14 25.12 equals 8 π 18.84 equals 6 π
8 is the square of the radius of the big circle, 6 is the square of the radius of the small circle
3.14 times (8 minus 6)
It's 3.14 times 2
Equal to 6.28

A ring, the circumference of the outer circle is 31.4cm, the circumference of the inner circle is 25.12cm, find the area of the ring. Quick

31.4÷3.14÷2=5(cm) 25.12÷3.14÷2=4(cm) 3.14×(5²-4²)=28.26(cm²)

The equation x & # 178; - 4ax + 3A + 1 = 0 one is greater than 2 one is less than 1

a>2

Factorization x quadratic plus 3x plus 2
If it can't be decomposed, it's OK

x²+3x+2
=x²+2x+x+2
=x（x+2)+（x+2）
=（x+2）（x+1）

Factorization of the fourth power of x plus the third power of 2x plus the square of x plus 1 plus 2 times (x plus the square of x)

The fourth power of x plus the third power of 2x plus the square of x plus 1 plus 2 times (x plus the square of x)
=x^4+2x^3+x^2+1+2(x+x^2)
=x^4+2x^3+x^2+1+2x+2x^2
=x^4+2x^3+3x^2+2x+1
=x^4+4x^3+6x^2+4x+1-2x^3-3x^2-1x
=(x+1)^4-2x^3-3x^2-1x
=(x+1)^4-x(2x^2+3x+1)
=(x+1)^4-x(2x+1)(x+1)
=(x+1)[(x+1)^3-x(2x+1)]
=(x+1)(x^3+3x^2+3x+1-2x^2+x)
=(x+1)(x^3+x^2+4x+1)

The following polynomials are factorized: 1. (AB + b) &# 178; - (a + b) &# 178; 2. (A & # 178; - X & # 178;) &# 178; - 4ax (x-a) &# 178;
fast
Urgent need

1（ab+b）²-（a+b)²=【（ab+b）+（a+b)】【（ab+b）-（a+b)】=（ab+a+2b）（ab-a)=a(ab+a+2b）(b-1)2（a²-x²）²-4ax（x-a)²=[(a+x)(a-x)]²-4ax（x-a)²=(a+x)²(a-x)
...

Fill in the blanks of factorization: 4ax & # 178; - ay & # 178; =?, MX & # 178; - my & # 178; =?, X & # 178; - 9y & # 178; =?

4ax²-ay²
=a(4x²-y²)
=a(2x+y)(2x-y)
mx²-my²
=m(x²-y²)
=m(x+y)(x-y)
x²-9y²
=x²-(3y)²
=(x+3y)(x-3y)

Factorization: 9A2 (X-Y) + 4B2 (Y-X)

9a2（x-y）+4b2（y-x）=9a2（x-y）-4b2（x-y）=（x-y）（9a2-4b2）=（x-y）（3a+2b）（3a-2b）．

Factorization: (1) a3-a (2) 4x2y + 4xy2 + Y3 (3) A2-B2 + 4b-4 (4) (X-2) 2 + X-8

(1) A3-a, = a (A2-1), = a (a + 1) (A-1); (2) 4x2y + 4xy2 + Y3, = y (4x2 + 4xy + Y2), = y (2x + y) 2; (3) A2-B2 + 4b-4, = a2 - (b2-4b + 4), = A2 - (b-2) 2, = (a + b-2) (a-b + 2); (4) solution 1: (X-2) 2 + X-8: = x2-4x + 4 + X-8 = x