In mathematical analysis, in the proof, whether the inequality preserving property of function limit must have an equal sign, some have no equal sign

In mathematical analysis, in the proof, whether the inequality preserving property of function limit must have an equal sign, some have no equal sign

There must be no mistake in taking an equal sign, it's "or" anyway. But when we consider it accurately, we can rule out the equation, and we'd better not take it

The length of BD is 1 and 2 / 3 times of CD, and the area of ACD is 3 and 2 / 3 square meters?
Quick, quick, quick, quick, quick, quick

The length of BD is one and two thirds of that of CD, that is BD: CD = 5:2,
The area of triangle ACD is 3 and 2 / 3 square meters, that is s △ ACD = 9 / 2 (square meters)
S △ abd: s △ ACD = BD: CD
S △ abd = 5S △ ACD / 2 = 5 / 2 * 9 / 2 = 11.25 (M2)

If the function f (x) = a Λ x (a Λ x-3a & #178; - 1) (a > 0 and a ≠ 1) is an increasing function in the interval [0, + ∞)
If the function f (x) = a Λ x (a Λ x-3a & #178; - 1) (a > 0 and a ≠ 1) is an increasing function in the interval [0, + ∞), the value range of a is obtained

This problem is a three-star problem, the picture did an hour
It's hard to say clearly without pictures. Please read it carefully
If there is anything you don't understand, please ask
 

The bottom area of the cone is 12.56, the height is 1m, and the radius and volume are in square meters?

V = 12.56 * 1 * 1 / 3 = 4.19 r = 12.56 / 3.14 / 2 = 2 that's about it

(a-b) ^ 2 - (B-A) ^ 3 factorization factor 4a (a-b) - 2 (B-A) ^ 2 (a-b) - A (B-A) (x + y) (x + 3) - x (y + x)

The washing machine is 60 cm long, 40 decimeters wide and 85 cm high. To make a cloth cover for the washing machine, at least what area of cloth is needed. Thank you, Dashen

Washing machine length 60 cm, width 40 decimeters, height 85 cm, make a washing machine cloth one hundred and sixteen

In natural numbers, all prime numbers except 2 are odd______ (judge right or wrong)

Because 2 is the only even prime number, all prime numbers except 2 are odd. So in natural numbers, all prime numbers except 2 are odd

A triangle road sign warning board with a bottom edge of 1.5 meters long and a height of 12 meters is painted on both sides of the warning board. It needs 0.8 kg of paint per square meter
How many kilos of paint will be used?

1.5x12x0.8 = 18x0.8 = 14.4kg

As shown in the figure, in △ ABC, ⊙ o with BC as diameter intersects AB at point D, CA is the tangent of ⊙ o, AE bisection ∠ BAC intersects BC at point E, CD at point F. (1) prove: CE = CF; (2) if SINB = 35, find the value of DF: CF

(1) It is proved that: BC is the diameter, ∠ BDC = 90 °, ∠ ADC = 90 ° and ∵ AFD + ∠ DAF = 90 °. ∵ CA is the tangent of ⊙ o, ≠ ACB = 90 ° and ∵ AEC + ∠ EAC = 90 ° and ∵ DAF = ∠ EAC, ∵ AFD = ∠ AEC, and ∵ EFC = ∠ AFD, ∵ EFC = ∠ AEC, ∵ CE = CF; (2) FG ⊥ AC is made at point g. ∵ right angle △ BCD, ∵ B + ∠ BCD = 90 ° and ∵ BCD + ACD = 90 ° and ∵ In the right angle △ CFG, sin ∠ ACD = SINB = fgfc = 35, ｜ DF: CF = FG: FC = 3:5

As shown in the figure, point P is in ∠ AOB, and points m and N are the symmetrical points of point P about OA and ob respectively. If the perimeter of △ PEF is 18cm, the length of Mn is calculated

18, add a condition e, f is the focus of Mn in OA, ob
The perimeter of △ PEF = PE + pf + EF, m and N are the symmetry points of point P about OA and ob respectively, so me = EP, NF = PF,
MN=ME+NF+EF=18