Given :
- Length of the rectangle is
- Breadth of the rectangle is
⠀
To Find :
- The area of the rectangle.
⠀
Solution :
We know that,
⠀
So, Substituting the given values :
Therefore,
- Area of the rectangle is
Let a and b = the numbers we must find.
a + 2b = 5.....Equation A
2a + b = 13.......Equation B
We have a system of equations in two variables.
I will solve A for little a.
a + 2b = 5
a = 5 - 2b
Now I will plug 5 - 2b for a in B.
2(5 - 2b) + b = 13
10 - 4b + b = 13
-3b = 3
b = -1
To find a, replace b with -1 in EITHER A or B.
I will use Equation A.
a + 2b = 5
a + 2(-1) = 5
a - 2 = 5
a = 7
The two numbers are -1 and 7.
Understand?
1. 15% decay
2. 50% growth
3. 15% growth
4. 5% growth
5. 50% decay
Remark
The area = 4*(x + 3) to start with. If you remove the brackets,
A = 4(x + 3)
A = 4*x + 3*4
A = 4x + 12 <<<<<< Answer for A
Part B
The area will become 4 times larger.
A = 4*(4x + 12)
A = 16x + 48
Argument
You may not be wholly satisfied with an unproved statement. I could prove it with algebra but it might be easier just to give an example.
Area = L * W
L = 10
W = 5
Area = 10*5
Area = 50
Now double both L and W
L = 20
W = 10
Area = L*W
Area = 20*10
Area = 200 which is 4 times the size of 50.