The discriminant of two elementary three unary quadratic mode roots 1. It is known that the equation x & sup2; - (K + 1) x + (1 △ 4) K & sup2; + 1 = 0 has two real roots. Try to find the value range of K 2. Proof: no matter m is any real number, the quadratic equation x & sup2; + (4m + 1) x + 2m-1 = 0 with respect to x always has two unequal real roots

The discriminant of two elementary three unary quadratic mode roots 1. It is known that the equation x & sup2; - (K + 1) x + (1 △ 4) K & sup2; + 1 = 0 has two real roots. Try to find the value range of K 2. Proof: no matter m is any real number, the quadratic equation x & sup2; + (4m + 1) x + 2m-1 = 0 with respect to x always has two unequal real roots

(K + 1) &# 178; - 4 * (1 / 4K & # 178; + 1) > equal to 0k & # 178; + 1 + 2k-k & # 178; - 4 > equal to 0k > equal to 3 / 2 (4m + 1) &# 178; - 4 (2m-1) > 016m & # 178; + 5 is always > 0, so no matter m is any real number, there are always two unequal real roots for the univariate quadratic equation x & # 178; + (4m + 1) x + 2m-1 = 0 of X

Factorization: - 25 / 49 + 0.01M square

0.01m^2-25/49
=(0.1m)^2-(5/7)^2
=(0.1m+5/7)(0.1m-5/7)

Given a + B = - 2, A-B = 2, decompose (a 2 + B 2-1) 2-4 A 2B 2 first, and then evaluate

The original formula = (A2 + b2-1-2ab) (A2 + b2-1 + 2Ab) = (a + B + 1) (a + B-1) (a-b + 1) (a-b-1) substituting a + B = - 2, A-B = 2, the original formula = 9

What is the weight of 1 cubic meter of water? How to calculate it?

1 m3 = 1000L
The mass of 1l water is 1kg
So: the mass of 1m3 water = 1000kg
Then its weight = 1000 * g (G is the local acceleration of gravity, generally 9.8m / s * s)

The principle of multiplication
Four people each write a greeting card, gather together first, and then each person takes a card selected by others. How many different ways of distribution are there?
There should be a process, thank you

We can consider four people as a, B, C, D, whether a left B's card or not when a took it; whether B left C's card or not when B took it; whether C left D's card or not when C took it; whether D's card must not be left, so a left B didn't leave B, B left C didn't

Find the special solution of differential equation DX: dy + YX = 0 satisfying y} x = 1 = 1

dy/dx=yx^2
dy/y=x^2dx
lny=x^3/3+lnC
y=Ce^(x^3/3)
Y (1) = 1 substituting: C = e ^ (- 1 / 3)
y=e^(x^3/3-1/3)

4 liter 50 ml = () liter 4600 cubic decimeter = () cubic meter 6.09 cubic decimeter = () liter = () milliliter 9.8 liter = () cubic decimeter = () cubic cm

4 liter 50 ml = (4.05) liter 4600 cubic decimeter = (4.6) cubic meter 6.09 cubic decimeter = (6.09) liter = (6090) ml 9.8 liter = (9.8) cubic decimeter = (9800) cubic cm

What is the difference between factorization and integral multiplication

Factorization is to transform a polynomial into the product of several polynomials, a & # 178; - B & # 178; = (a + b) (a-b)
Integral multiplication is the expansion of the product of several polynomials into the form of polynomials (a + b) (a-b) = A & # 178; - B & # 178;

Find the plane equation and normal equation of the tangent plane of the elliptic sphere x * 2 + 3Y * 2 + 2Z * 2 = 6 at the point (1,1,1)
Find the plane equation and normal equation of the tangent plane of the elliptic sphere x * 2 + 3Y * 2 + 2Z * 2 = 6 at the point (1,1,1)

Let f (x, y, z) = x ^ 2 + 3Y ^ 2 + 2Z ^ 2-6,
By deriving x, y and Z, we get 2x, 6y and 4Z,
So the normal vector is (2,6,4),
So the tangent plane equation is 2 (x-1) + 6 (Y-1) + 4 (Z-1) = 0, which is reduced to x + 3Y + 2z-6 = 0,
The normal equation is (x-1) / 2 = (Y-1) / 6 = (Z-1) / 4, which is reduced to (x-1) / 1 = (Y-1) / 3 = (Z-1) / 2

How many kilometers per hour can a car run at 120 miles

Now 99% of the drivers in China can't understand the relationship between "Mai" and "km". I can't understand it
People who have met, whether old drivers or novices, whether doctors or primary school educated people,
No matter who is good at English or who can only speak byebye, as long as they can drive, they don't know why
It seems that if you don't say "Mai", you can't drive, just like the four one upstairs
Like, many drivers "step" all day long
In fact, they say "Mai" in English -- "Mile" or "miles"
If you pronounce it slightly, you can't pronounce the kilometer as "Mai"!
The conversion relationship between the two is: 1km = 0.621mile, 1mile = 1.61km
In other words, 60 mph is equivalent to 97 km / h!
60 km / h is 37 mph!
So "Mai" and "km" are both length units, but they are totally different concepts
Please don't call speedometer "step speedometer" any more
It's time to make a unit
By the way, "YD" is a unit of length corresponding to "m",
Their conversion relations are as follows:
1yd = 0.914m,1m = 1.09yd；
60 yards per hour is equivalent to 55 meters per hour