9.Which of the following are used to represent unknown quantities in algebra? A) Upper case letters B) Lower case letters C) Onl
2 answers:
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Answer:
Step-by-step explanation:
[1] 2x + y = -1
[2] x - 2y = -8 <------- given linear equations
Graphic Representation of the Equations : ----> given in attatchment
y + 2x = -1 -2y + x = -8 < ----- point where they connect is shown in graph
Solve by Substitution :
// Solve equation [2] for the variable x
[2] x = 2y - 8
// Plug this in for variable x in equation [1]
[1] 2•(2y-8) + y = -1
[1] 5y = 15
// Solve equation [1] for the variable y
[1] 5y = 15
[1] y = 3
// By now we know this much :
x = 2y-8
y = 3
// Use the y value to solve for x
x = 2(3)-8 = -2
Solution :
{x,y} = {-2,3}
Answer:
Step-by-step explanation:
The perimeter of a rectangle can be calcualated with this formula:
Where "l" is the lenght and "h" is the height.
The area of a rectangle can be found with this formula:
Where "l" is the lenght and "h" is the height.
In this case we know that:
Therfore, we can susbsitute them into and solve for "h" in order to find its value:
Find two number whose sum is 3 and whose product is -40. These are -5 and 8. Then, factorizing, we get:
The positive value is the height. Then:
Since the length is 3 centimeters greater than its height, we get that this is: Then:
Substituting values into , we get that the perimeter is: