Answer:
The even numbers between 0 and X represents an arithmetic sequence with a common difference of 2
The rule of arithmetic sequence = a + d(n - 1)
Where a is the first term and n is the number of terms
So, for the even numbers between 0 and X
The first term = a = 0
d = 2
So, we need to find n at the last term which is X
∴ X = 0 + 2 ( n -1 )
∴ n - 1 = X/2
∴ n = X/2 + 1
The sum of the arithmetic sequence = (n/2) × (2a + (n−1)d)
Substitute with a and d and X
So, the sum = (n/2) * (2*0 + (n−1)*2)
= (n/2) * ((n−1)*2)
= n(n-1)
= (X/2 + 1) * (X/2)
= X/2 by (X/2 + 1)
So, The quick way to add all even numbers between 0 and X always works.
A + 3A = 120
4A = 120
A = 30
B = 90
Answer:
-20
Step-by-step explanation:
(-12) + (-8)
-12 - 8
-20
The formula for the area of a triangle is A = 1/2 x b x height. But, we don't have the height here. To find the height, we can use the Pythagorean theorem.
With Pythagorean theorem, we'll be finding one of the legs. If we split the original triangle in 1/2 from the vertex to the base, we now have two right triangles. Both of these right triangles have a 30 cm hypotenuse and one 13 cm leg (remember we divided the entire original triangle in half).
30^2 = 13^2 + b^2
169 + b^2 = 900
b^2 = 731
b =
Now that we know the height of the triangle, we can find the area.
A = 1/2 x 26 x
A = 13 x
A = 351.48
The final area, rounded to the nearest whole number is 351 centimeters squared.
Note: Please know that depending on if the answer rounded before using it to find the area, the final answer may then be rounded to 352.
Hope this helps! :)