What is 1 + 2 + 3 + 4. + 998 + 999,

(1 + 999) × 999 divided by 2 = 499500

999 × 999 + 1999 = 1000 × 1000?

999×999+1999
=999×999+999+1000
=999×(999+1)+1000
=999×1000+1000
=(999+1)×1000
=1000×1000
=1000000
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Thinking: 1001 + 1000 + 999 + 998 + +Is the result of 4 + 3 + 2 + 1 odd or even?
It's like an odd number

If (1001 + 1) △ 2 = 501 is odd, there are 501 odd numbers
So, sum is odd

It is known that the factorization result of the quadratic trinomial 2x square + MX + n of X is [2x-3] [x + 1], and M is obtained

Because [2x-3] [x + 1] = 2 * x ^ 2-x-3 = 2x square + MX + n
Then compare the corresponding values
M = - 1, n = - 3

It is known that the result of the factorization of the quadratic trinomial 4x square MX + n is (2x + 3) (2x-3)

（2x+3）（2x-3）
=4x²-9
Then in the original formula 4x & # 178; - MX + N
m=0
n=-9

On the square + 11x + m factorization of the quadratic trinomial 2x of X, one of the factorization results is x-3. Can you find the value of M?

Because the former coefficient of quadratic term is 2, and the latter factor is (x-3), so the coefficient of another factor must be 2, which can be set as (2x + n), that is: 2x & sup2; + 11x + M = (x-3) (2x + n) expanded to: 2x & sup2; + 11x + M = 2x & sup2; + (n-6) x-3n, so: n-6 = 11, M = - 3NN = 17, M = - 51

(X-2) & # 178; = 6-x to solve the equation

x^2-4x+4=6-x
x^2-3x+2=0
(x-1)(x-2)=0
X = 1 or x = 2

Solving equation (x-1) / (x + 1) - 6 / (X & # 178; - 1) = 1

(x-1) / (x + 1) - 6 / (xsquare-1) = 1
(x-1) Square-6 = x Square-1
Xsquare - 2x + 1-6 = xsquare - 1
2x=-5+1
2x=-4
x=-2
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Solve equation 11 (1 + x) 2 = 18.59

1+x=18.59/22
1+x=0.845
x=-0.155

What is 1 + 2 + 3 + 4. + 998 + 999,