How much is the sum of the first 2012 items if x = 1

How much is the sum of the first 2012 items if x = 1

When x = 1, x-3x ^ 2 + 5x ^ 2-7x ^ 2 + 9x ^ 2 -. - 2012x ^ 2 = (- 2) * 1006 = - 2012

It is known that angle a is two times of angle B, and three times of angle a is equal to the complementary angle of angle B. the degree of ∠ a · ∠ B is calculated

∠A=2∠B (1)
3∠A=180°-∠B (2)
(1) Substituting (2) to get:
6∠B=180°-∠B
∠B=180/7°
∠A=360/7°

Given that angle a = 3 angle B, the remainder angle of angle a is 5 times less than the complement angle of angle B by 10 ° and the degree of angle A and angle B is calculated?
Not one equation, one answer

a=3b
5(90-a)=180-b-10
450-5a=170-b
5a-b=280
15b-b=280
14b=280
b=20
a=3b=3×20=60
Angle a = 60
Angle B = 20

Fill seven numbers 1, 2, 3, 6, 7, 8 and 9 in the following formula to make them hold: () () - () = () + () = () ()

23-6=8+9=17

Fill nine different numbers 1,2,3,4,5,6,7,8,9 in () respectively to make the following three formulas hold
（）＋（）＝（）　　　　（）－（）＝（）　　　　（）×（）＝（）

4+5=9 8-1=7 2×3=6

Add "+" or "-" before the numbers 2, 3, 4, 5, 6, 7, 8 and 9. The sum of them is 10. Please explore at least four formulas

2+3-4+5-6-7+8+9=10
2+3-4-5+6+7-8+9=10
-2+3+4+5+6-7-8+9=10
-2-3-4+5+6+7-8+9=10
There is also a - sign in front of them
You can get four more

Add "+" or "'" before the numbers 1, 2, 3, 4, 5, 6, 7, 8 and 9 to make the result 15. The formula is? Please write two

1＋2＋3—4—5—6＋7＋8＋9＝15
1—2＋3＋4—5＋6＋7—8＋9＝15

There is a list of addition formula, 4 + 2, 5 + 8, 6 + 14, 7 + 20 The first addend of these formulas is arranged according to the law, and the second addend is also arranged according to the law. What is the 99th formula______ ．

According to the analysis, the number before the plus sign of the 99th addition is 99-1 + 4 = 102; the number after the plus sign is 6 × (99-1) + 2 = 590. So the 99th addition is 102 + 590. So the answer is 102 + 590

According to a certain law of the formula: 4 + 2, 5 + 8, 6 + 14, 7 + 20 So the 100th formula is______ ．

According to the above analysis, the 100th formula is: (4 + 99) + (2 + 99 × 6) = 103 + (2 + 594) = 103 + 596, so the answer is: 103 + 596

There is a list of addition formula, 4 + 2, 5 + 8, 6 + 14, 7 + 20 The first addend of these formulas is arranged according to the law, and the second addend is also arranged according to the law. What is the 99th formula______ ．

According to the analysis, the number before the plus sign of the 99th addition is 99-1 + 4 = 102; the number after the plus sign is 6 × (99-1) + 2 = 590. So the 99th addition is 102 + 590. So the answer is 102 + 590