Answer:
Step-by-step explanation:
- 7 + 3x - 12x = 3x + 1
- 7 - 9x = 3x + 1
- 3x + 9x = 7 - 1
- 12x = 6
- x = 6/12
- x = 1/2
It has one solution
Answers:
x = -8/5 or x = 8/5
Sum of the first ten terms where all terms are positive = 4092
========================================================
Explanation:
r = common ratio
- first term = 4
- second term = (first term)*(common ratio) = 4r
- third term = (second term)*(common ratio) = (4r)*r = 4r^2
The first three terms are: 4, 4r, 4r^2
We're given that the sequence is: 4, 5x, 16
Therefore, we have these two equations
Solve the second equation for r and you should find that r = -2 or r = 2 are the only possible solutions. If r = -2, then 5x = 4r solves to x = -8/5. If r = 2, then 5x = 4r solves to x = 8/5.
-----------------
To find the sum of the first n terms, we use this geometric series formula
Sn = a*(1 - r^n)/(1 - r)
We have
- a = 4 = first term
- r = 2, since we want all the terms to be positive
- n = 10 = number of terms to sum up
So,
Sn = a*(1 - r^n)/(1 - r)
S10 = 4*(1 - 2^10)/(1 - 2)
S10 = 4*(1 - 1024)/(-1)
S10 = 4*(-1023)/(-1)
S10 = 4092
Let number of fives = x then number of ones = 3x and number of tens = x - 1
so we can create the equation
x + 3x + x-1 + y = 26 where y = number of twenties
so
5x + y = 27
also we have the equation
5x + 3x + 10(x - 1) + 20y = 120
18x + 20y = 130..................................(1)
5x + y = 27 multiply by -20:-
-100x - 20y = -540..............................(2)
Adding equation (1) and (2)
-82x = -410
x = 5, that is 5 fives
Now plug x = 5 into equation 1:-
18(5) + 20y = 130
20y = 40
y = 2 , that is 2 twenties
So the answer is there are (3x) = 15 ones , 5 fives, 4 tens and 2 twenties
Answer:
hmmm interesting
Step-by-step explanation:
Answer:
Erin gets £90
Step-by-step explanation:
Ratio = 5 : 2 : 7
Money with Erin = 5x
Money with Faye = 2x
Money with Sachin = 7x
Faye gets £90 less than Sachin
7x - 2x = 90
5x = 90
x = 90/5
x = 18
Money with Erin = 5*18 = 90
