5x + y = 9....multiply by 7
10x - 7y = -18
----------------
35x + 7y = 63 (result of multiplying by 7)
10x - 7y = -18
----------------add
45x = 45
x = 45/45
x = 1
5x + y = 9
5(1) + y = 9
5 + y = 9
y = 9 - 5
y = 4
solution is : (1,4)
=========================
-4x + 9y = 9
x - 3y = -6 ....multiply by 4
----------------
-4x + 9y = 9
4x - 12y = -24 (result of multiplying by 4)
---------------add
- 3y = - 15
y = -15/-3
y = 5
x - 3y = -6
x - 3(5) = -6
x - 15 = -6
x = -6 + 15
x = 9
solution is : (9,5)
In order to figure this out you need to use
Descartes Rule. I attached a picture showing Descartes Rule. If the signs changes for when x is positive then the number of times it changes are the possible positive solution. If the sign changes when x is negative then the number of times it changes are the possible negative solutions. With that said the answer is A. View the picture I have attached for the possible + - and imaginary solutions.
Answer = A) One possible positive solution.
Answer:
they both charge the same cost per linear feet
Step-by-step explanation:
It appears that each company has a base charge for installation, which is the dollar value where each line begins at the y-axis. Both lines have the same slope and if you count, the cost is $75 per 5 linear feet.
Answer:
f(x)=(x-1)^2+5 with domain x>1 and range y>5 has inverse g(x)=sqrt(x-5)+1 with domain x>5 and range y>1.
Step-by-step explanation:
The function is a parabola when graphed. It is in vertex form f(x)=a(x-h)^2+k where (h,k) is vertex and a tells us if it's reflected or not or if it's stretched. The thing we need to notice is the vertex because if we cut the graph with a vertical line here the curve will be one to one. So the vertex is (1,5). Let's restrict the domain so x >1.
* if x>1, then x-1>0.
* Also since the parabola opens up, then y>5.
So let's solve y=(x-1)^2+5 for x.
Subtract 5 on both sides:
y-5=(x-1)^2
Take square root of both sides:
Plus/minus sqrt(y-5)=x-1
We want x-1>0:
Sqrt(y-5)=x-1
Add 1 on both sides:
Sqrt(y-5)+1=x
Swap x and y:
Sqrt(x-5)+1=y
x>5
y>1
