Cross section of the canal. Calculate the cross section area of the canal. The width of the canal mouth is 5 meters, the width of the canal bottom is 3 meters, the depth of the canal is 2 meters. How many square meters is the cross section area?

(5 + 3) * 2 / 2 = 8 square meters

The cross section of a canal is trapezoidal, with a depth of 0.8 meters, a bottom width of 1.2 meters, and a mouth width of 2 meters. What is the cross section area of square meters?

(1.2 + 2) × 0.8 △ 2 = 3.2 × 0.8 △ 2 = 1.28 (M2) a: the cross-sectional area is 1.28 m2

The cross section of a newly excavated canal is trapezoidal. The width of the canal mouth is 2.8 meters, the width of the canal bottom is 1.4 meters, and the depth of the canal is 1.2 meters?

(1.4 + 2.8) × 1.2 △ 2, = 4.2 × 1.2 △ 2, = 2.52 (square meters); a: its cross-sectional area is 2.52 square meters

We know that a = a + 2, B = the square of a + 5a-19, where - 7 < a < 3. (1) decompose B-A into factors. (2) compare the size of a and B

1)B-A
=(a^2+5a-19)-(a+2)
=a^2+5a-19-a-2
=a^2+4a-21
2) Because - 7 < a < 3, so (a + 7) (A-3)

Make two cuboid boxes of different sizes, small carton: length a, width b, height C, large carton: length 1.5A, width 2B, height 2C. (1) how many square centimeters do two cartons share
(2) How much more material does a large carton use than a small carton

1. Using 8ab + 8ac + 10bc 2, the large carton uses 4AB + 4ac + 6BC more than the small carton

π - 6 + | π - 6 | = (). If (a + 3) &# 178; + | 4 - 6 | = 0, then the relationship between a and# 178; and 2b is ()

π-6+| π - 6 |=( 0).
If (a + 3) &# 178; + | 4 - B | = 0
A+3=0,4-B=0
A=-3,B=4
A²=9,2B=8
∴A²＞2B

Read the following: compare a ^ 2-B ^ 2 + 2 / 2 with a ^ 2-2b ^ 2 + 1 / 3

Detailed

It is known that a = a + 2, B = a2-a + 5, C = A2 + 5a-19, where a > 2. (1) prove that B-A > 0, and point out the size relationship between a and B; (2) point out which is bigger between a and C? Give reasons

(1) B-A = (A-1) 2 + 2 > 0, so b > A; (2) C-A = A2 + 5a-19-a-2, = A2 + 4a-21, = (a + 7) (A-3). Because a > 2, so a + 7 > 0, so when 2 < a < 3, a > C; when a = 3, a = C; when a > 3, a < C

It is known that a = a + 2, B = a2-a + 5, C = A2 + 5a-19, where a > 2. (1) prove that B-A > 0, and point out the size relationship between a and B; (2) point out which is bigger between a and C? Give reasons

(1) B-A = (A-1) 2 + 2 > 0, so b > A; (2) C-A = A2 + 5a-19-a-2, = A2 + 4a-21, = (a + 7) (A-3). Because a > 2, so a + 7 > 0, so when 2 < a < 3, a > C; when a = 3, a = C; when a > 3, a < C

(1) 2.1 power of 0.3 and 3.2 power of 4
(2) 3.5 to the negative 1.9 power and 8 to the 1.5 power

The 2.1 power of 0.3 is less than 1, and the 3.2 power of 4 is greater than 1
The negative 1.9 power of 3.5 is less than 1, and the 1.5 power of 8 is greater than 1

Cross section of the canal. Calculate the cross section area of the canal. The width of the canal mouth is 5 meters, the width of the canal bottom is 3 meters, the depth of the canal is 2 meters. How many square meters is the cross section area?