(- 81) △ 2 and 1 / 4 × 4 / 9 × (- 16) -The result is () A.4 B.-4 C.2 D.-2

(- 81) △ 2 and 1 / 4 × 4 / 9 × (- 16) -The result is () A.4 B.-4 C.2 D.-2

Original formula = (- 81) / 2 and 1 / 4 * 4 / 9 * (- 16)
=(- 81) / 9 / 4 * 4 / 9 * (- 16)
=（-81）/1*（-16）
=（-81）*（-16）
=1296

How to solve the linear equation of one variable with decimal coefficient in numerator and denominator
（X/0.7）-（0.17-0.2X/0.03）=1

(10x/7)-(0.17-20x/3)=1
30x-1.19-140x=21
-110x=21+1.19
-110x=22.19
x = - 22.19/110
x = - 2219/11000

How to calculate 999 plus 999 times 999
The answer is urgent before 9 o'clock

Curve C1: x2 / 16 + Y2 / 4 = 1, curve C2: x2 = 4Y
If the ordinate of point a is 1, find → AB * → AC
Finding the maximum of s ⊿ ABC

a^2-3a __ __ =2a^2 2a

a^2-3a +a^2+5a=2a^2 2a

As shown in the figure, in △ ABC, e is a point on BC, EC = 2be, and point D is the midpoint of AC. suppose that the areas of △ ABC, △ ADF, and △ bef are s △ ABC, s △ ADF, and s △ bef respectively, and s △ ABC = 12, then s △ adf-s △ bef=______ ．

∵ point D is the midpoint of AC, ∵ ad = 12ac, ∵ s △ ABC = 12, ∵ s △ abd = 12S △ ABC = 12 × 12 = 6. ∵ EC = 2be, s △ ABC = 12, ∵ s △ Abe = 13s △ ABC = 13 × 12 = 4, ∵ s △ abd-s △ Abe = (s △ ADF + s △ ABF) - (s △ ABF + s △ BEF) = s △ adf-s △ bef

What is 1 = 5 2 = 10 3 = 15 4 = 20 5

Because 1 = 5, so 5 = 1
Don't look at 2 = 10, 3 = 15, 4 = 20 to launch 5 = 25 fans or yours. It's better to be simple and smart

The value of P = | 1-2x | + | 1-3x | + | 1-4x | +... + | 1-10x | is constant. What's the value of P? Algorithm and problem solving process (the simpler the better)

The idea is as follows, because the formula is a constant, it means that there is no longer X in the simplified equation. Take the first absolute value | 1-2x | as an example, after the absolute value sign is removed, it is nothing but 1-2x or 2x-1, that is to say, the sign before x can be positive or negative. Finally, after the nine absolute value signs are removed, all x are offset completely, equation 9

What is 68 ° 51'36 "equal to?

68.86\
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How to get 2 * sin (x + 30) + A from 3 * SiNx + cosx + A

This is the application of the formula (sum difference to product, product to sum difference)
sin30=1/2 cos30=√3/2
Original formula = 2 * (√ 3 / 2 * SiNx + 1 / 2 * cosx) + A
=2*（cos30*sinx+sin30*cosx）+a
=2*sin（x+30）+a
Sum difference is a set of formulas