I would say around 25 to 35
Gauss' method for addition relies on the fact that you can 'pair' certain numbers together. Look at the example:
1+2+3+4+5+6+7+8+9+10
We could manually add all these together from left to right but a clever way to think about this is if we add together the ends of the sum (10+1) we get 11. If we then move one in from the ends and add these (2+9) we also get 11. This means that 1+2+...+9+10 is the same as 11+11+...+11+11.
Because each 2 numbers adds to 11 we know the total number of 11's we have to add together is the length of the sum divided by 2. In our case 5 (10 ÷ 2). We need to add 5 lots of 11 to get our answer. This is the same as 11 × 5 which is easily seen to be 55.
(If you add the 10 numbers together on a calculator you'll see 1+2+3+4+5+6+7+8+9+10 = 55) so this method really makes it a lot quicker.
Looking at your sequence, if we pair the ends together we get 401 (400+1) and we multiply this by the length of the sequence divided by 2. In your case, 200 (400 ÷ 2).
So the sum of all the numbers from 1 to 400 must be 401 × 200 = 80,200.
Remember the steps:
1. Pair the ends together and add them
2. Times this number by the length of the sequence halved
Hope this helps.
Answer:
x=-2, y=-6
Step-by-step explanation:
Simple substitution.
Since y is isolated in one of the equations already, you can plug it into the second equation.
x - 2(3x) = 10
x - 6x = 10
-5x = 10
x = -2
Sub. x = -2 into 3x = y:
3(-2) = y
y = -6
If my calculations are correct the answer is cut your answer in half
Answer:
he area that is un-shaded is (x-3)(x-6).
The entire area is (2x+2)(3x-4).
Area of the shaded region is:
(2x+2)(3x-4) - (x-3)(x-6) =
(6x2-2x-8) - (x2-9x+18) =
6x2-2x-8-x2+9x-18 =
5x2+7x-26 hopes this help btw (;
