Let a and B be the two real roots of the equation x Λ 2 + x-2011 = 0, then the value of a Λ 2-B is?

Let a and B be the two real roots of the equation x Λ 2 + x-2011 = 0, then the value of a Λ 2-B is?

A is substituted into the equation: A & # 178; + a-2011 = 0
From the relationship between root and coefficient: a + B = - 1
Subtraction of two formulas: A & # 178; - b-2011 = 1
Transfer: A & # 178; - B = 2012

On the equation 3x ^ 2-6 (t-1) x + T ^ 2 + 1 = 0 of X, if the sum of the absolute values of the real roots is 2, then the real number T=

Let two be X1 and x2
Because X1 * x2 = (T ^ 2 + 1) / 3 > 0
(1) If both are positive
Then X1 + x2 = 2 = 2 (t-1), t = 2, but the discriminant

The length of one express train is 70 meters, and that of the other local train is 80 meters. If the two trains go in the same direction, the express train will meet and leave the local train,
It only takes 12 seconds. What's the speed of the express train and the local train?

Lack of conditions:
The fast train is 70 meters long, and the slow train is 80 meters long. If you run in the same direction, it takes 20 seconds for you to catch up and leave completely; if you run in the opposite direction, it takes 4 seconds for you to meet and leave, so you can find the speed of the two trains
Let the fast train speed be x m / s and the slow train speed be y m / s
20（X-Y）=80
4（X+Y）=150
The solution is: x = 20.75 M / S = 74.7 km / h
Y = 16.75 M / S = 60.3 km / h
A: the fast train speed is 74.7 km / h, and the slow train speed is 60.3 km / h

The polar coordinate equation ρ = 2Sin θ is transformed into the ordinary equation x & # 178; + Y & # 178; - 2Y = 0

Y / P = sin, take it into the above equation, and then replace P with x2 + Y2 under the root sign

There is a batch of cement in a construction site. Two fifths of it was used in the first day, and 35% in the second day. There are still 25 tons left. How many tons of this batch of cement?

25÷（1－2/5－35%）
＝25÷1/4
= 100 (tons)

The center angle of the sector AOB is 120 C, and the motion (vector) OC = xoa + yob on the arc ab. find the maximum value of X + y,

Let radius be 1, angle COA = @, do CD / / AO, CE / / Bo, then OE = x, OD = y, angle Cao = 60 degrees and Y / sin @ = x / sin (120 degrees - @) = 1 / sin60 degrees, so x + y = [1 / sin60 degrees] [sin @ + sin (60 degrees + @)] = [1 / sin60 degrees] [sin @ + sin60 degrees cos @ + cos60 degrees sin @] = [1 / sin60 degrees] root sign 3 [sin

A pile of yellow sand weighs nine fourths of a ton. How many times can it be transported one fourth of a ton at a time? If it is transported one fourth of a ton at a time, how many times can it be transported?

A pile of yellow sand weighs nine fourths of a ton. How many times can it be transported?
9 / 4 △ 1 / 4 = 9 times
How many times can we finish if we transport a quarter of them each time?
1 △ 1 / 4 = 4 times

If the line L and the line 3x-4y + 5 = 0 are axisymmetric, then the equation of the line L is
The answer is 3x + 4Y + 5 = 0

Is it about X-axis symmetry?
The abscissa of two points symmetrical about X axis is the same, and the ordinate is the opposite
It's the same with straight lines
X does not change, y becomes the opposite number
So it's 3x + 4Y + 5 = 0

There are 270 female employees in a factory, which is 9 / 7 of the male employees. How many employees are there in the whole factory

X male staff
9X/7=270
X=270*7/9
X=210
Total = 210 + 270 = 480

Decompose the following into factors - 5x & # 178; + 10xy & # 178; - 25xy & # 178;
（m+n）²-m-n
a²（a-b）-6ab（b-a）
2n power of 3x - 2n + 1 power of 15x
a² b-5ab
6（p+q）²-12（p+q）

-5x²+10xy²-25xy²
=-5x²-15xy²
=-5x(x+3y²)
（m+n）²-m-n
=(m+n)²-(m+n)
=(m+n)(m+n-1)
a²（a-b）-6ab（b-a）
=a²(a-b)+6ab(a-b)
=a(a-b)(a+6b)
2n power of 3x - 2n + 1 power of 15x
=2n power of 3x (1-5x)
a² b-5ab
=ab(a-5)
6（p+q）²-12（p+q）
=6(p+q)(p+q-2)