The answer would be C. Hope this helps :)
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:
5.14 km
Step-by-step explanation:
A semicircle is 1/2 of a circle so the perimeter is just 1/2 of the circumference
C = 2 * pi r for a circle so for a semicircle
1/2* 2* pi *r
pi*r
3.14 * 1
3.14
If we want to include the piece that closes the semicircle, we need to add the diameter
d = 2r = 2(1) = 2
2+3.14 = 5.14
Answer:
Step-by-step explanation:
P(-2,-1) and Q(4,3)
average of x-coordinates = (-2+4)/2 = 1
average of y-coordinates = (-1+3)/2 = 1
midpoint of PQ: (1,1)
distance between midpoint and Q = √((4-1)²+(3-1)²) = √13
(x-1)² + (y-1)² = 13
Answer:
The line slopes upwards from left to right wit a positive gradient and cuts the y-axis at y=2 and the x-axis at x=-3/2
Step-by-step explanation:
We first rearrange the equation to the order y=mx+c where m is the gradient and c the y intercept.
3y=4x+6
y=(4/3)x+2
The gradient is therefore 4/3 and the y intercept is 2.
At the c intercept, y=0
0=(4/3)x +2
(4/3)x=-2
x=-2×3/4
=3/2
The line slopes upwards from left to right with a positive gradient and cuts the y-axis at y=2 and the x-axis at x=-3/2
