Answer:
700 lei
Step-by-step explanation:
You have a geometric sequence for which you know the common ratio and the last term.
There are only three terms, so you can solve the problem in either of two ways.
1. The brute force method
(easiest for only a few terms)
Each term is half the one before it, so each term is double the one after it.
3rd term = 100 lei
2nd term = 200
1st term = 400
Total = 700 lei
Oana spent 700 lei
2. Using formulas (best for longer sequences)
The general formula for your sequence is
aₙ = a₁rⁿ⁻¹
For your sequence,
a₃ = 100; r = 0.5
(a) Calculate a₁
Set the last term equal to the general formula.
a₃ = a₁(0.5)ⁿ⁻¹
100 = a₁(0.5)² = 0.25a₁
a₁ = 100/0.25 = 400
(b) Calculate the sum
The general formula for the sum of a geometric sequence is
Oana spent 700 lei.
Answer:
f\left(x\right)=x^3-x
Step-by-step explanation:
Answer:
tanx = sinx/cosx
Step-by-step explanation:
Given the expression
sin x cos x tan x = 1 - cos^2x
According to trigonometry identity
tan x = sinx/cosx
Substitute into the expression. From LHS
sin x cos x tan x
= sin x cos x (sinx/cosx)
= sin²x
Also since sin²x+cos²x = 1
Hence sin²x = 1 - cos²x (RHS)
The correct option is therefore tanx = sinx/cosx
Answer:
x=-33/5 y=29/5
Step-by-step explanation:
Let's solve your system by substitution.
3x+y=−14;2x−y=−19
Solve
3x+y=−14 for y:
3x+y=−14
3x+y+−3x=−14+−3x(Add-3x to both sides)
y=−3x−14
Next is to substitute −3x−14 in for y 2x−y=−19:
2x−y=−19
2x−(−3x−14)=−19
5x+14=−19(Simplify both sides of the equation)
5x+14+−14=−19+−14(Add -14 to both sides)
5x=−33 Dived both sides by 5
5x/5=-33/3
x=−33/5 since you can't dived and a fraction is another form of division you keep it this way.
Step: Substitute -33/5 for x in y=−3x−14:
y=−3x−14
y=−3(-33/5)-14
y=29/5
(Simplify both sides of the equation)(since you can't dived and a fraction is another form of division you keep it this way.)
So
x=-33/5 and y=29/5
Pls mark brailest this took me a long time to write out lol. Hope this truly helps! Send a heart if so, so I can keep spreading the help!
The correct answer is F(-2)=-23
