Hello from MrBillDoesMath!
Answer:
225
Discussion:
Sum ( 2n - 1) from n = 1 to 15
= Sum(2n) - Sum(1) from n = 1 to 15
= 2 Sum(n) - Sum(1) from n = 1 to 15
= 2* 15(15+1)/2 - (1 + 1 + .. + 1)
The first value comes from the fact that the sum of the first n integers is n(n+1)/2. The latter value sums 15 1's.
= 2 * 15 * 16/2 - 15 => 2/2 = 1
= 15*16 - 15 => 15*16 = 240
= 240 - 15
= 225
Thank you,
MrB
Answer:
$10
Step-by-step explanation:
Let a = the amount Angela has saved.
Let e = the amount Eli has saved.
"Eli has saved $8 more than 1/3 of Angela's savings."
e = a/3 + 8
"If they each save $10 more." then
Eli will have: e + 10
Angela will have a + 10
"Eli will have saved $4 more than Angela's savings."
e + 10 = a + 10 + 4
This equation simplifies to: e = a + 4
We have a system of two equations in two variables.
e = a/3 + 8
e = a + 4
Since both equations are solved for e, we just equate the right sides.
a/3 + 8 = a + 4
Subtract a/3 from both sides. Subtract 4 from both sides.
a/3 - a/3 + 8 - 4 = a - a/3 + 4 - 4
4 = (2/3)a
Multiply both sides by 3/2
(3/2)4 = (3/2)(2/3)a
6 = a
a = 6
Angela has $6.
e = a + 4 = 6 + 4 = 10
Eli has $10.
Answer:
B
Step-by-step explanation:
25 x 25= 625
625-1= 624
B= y= -(200 + 1) which to the square root = 625