This is a refreshing question!
We are given that
f(r)=ar+b, and
Sum f(r) =125 for r=1 to 5
Sum f(r) = 475 for r=1 to 10.
and we know, using Gauss's method, that
G(n)=sum (1,2,3.....n) = n(n+1)/2 or
G(n)=n(n+1)/2
Sum f(r) =125 for r=1 to 5
=>
sum=a(sum of 1 to 5) + 5b => G(5)a+5b=125 [G(5)=15]
15a+5b=125 ...................................................(1)
Similarly, Sum f(r) = 475 for r=1 to 10 => G(10)a+5b=475 [G(10)=55]
=>
55a+10b=475.................................................(2)
Solve system of equations (1) and (2)
(2)-2(1)
55-2(15)a=475-2(125) => 25a=225 =>
a=9
Substitute a=9 in 1 => 15(9)+5b=125 => 5b=-10
b=-2
Substitute a and b into f(r),
f(r)=9r-2
check: sum f(r), r=1,5 = (9-2)+(18-2)+(27-2)+(36-2)+(45-2)=135-10=125 [good]
We define the sum of f(r) for r=1 to n as
S(n)=sum f(r) for r=1 to n = 9(sum 1,2,3....n)-2n = 9n(n+1)/2-2n = 9G(n)-2n
S(n)=9n(n+1)/2-2n
checks:
S(5)=9(15)-2(5)=135-10=125 [good]
S(10)=9(55)-2(10)=495-20=475 [good]
Hence
(a)
S(n)=sum f(r) for r=1,n
= 9(sum i=1,n)+n(-2)
= 9(n(n+1)/2 -2n
=(9(n^2+n)/2) -2n
(b) sum f(r) for i=8,18
=sum f(r) for i=1,18 - sum f(r) for i=1,7
=S(18)-S(7)
=(9(18^2-18)/2-2(18))-(9(7^2-7)/2-2(7))
=1503-238
=1265
The solution of 0.6(4-2x)=20.5-(3x+10) is x = 4.5
<u>Solution:</u>
Given, expression is 0.6 ( 4 – 2x ) = 20.5 – ( 3x + 10 )
We have to solve the above given equation for x.
Now, take the equation
We have to use BODMAS rule. BODMAS means sequence of operations which is brackets, order, division, multiplication, addition and then subtraction
On solving the brackets, we get
Now multiplication is given preference
Now subtraction is done
Now division is performed
Hence, the value of x is 4.5
Answer:
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Step-by-step explanation:
yee
Answer:
Hey there!
1) To solve this, we want to know the volume of the first cylinder, which using the cylinder volume formula, we find is roughly 3079 cm^3. If the water is poured into the second cylinder, we find that the height is about 9.8 cm.
2) First, we should know that 1000 cm^3=1 liter. Volume of 1 cm tank height: 3848 cm^3, or 3.848 l. Volume for 20 cm tank height= 76.96 l. It takes about 7.7 hrs for the water level to fall 20 cm.
3) Cylinder volume formula gives us the answer to be 176 m^3 as the volume.
Hope this helps :)
Answer:
A is 13
Step-by-step explanation:
That is because you have to K C C. Since there is no l9onger negatives, you can add
