Well, we could try adding up odd numbers, and look to see when we reach 400. But I'm hoping to find an easier way.
First of all ... I'm not sure this will help, but let's stop and notice it anyway ...
An odd number of odd numbers (like 1, 3, 5) add up to an odd number, but
an even number of odd numbers (like 1,3,5,7) add up to an even number.
So if the sum is going to be exactly 400, then there will have to be an even
number of items in the set.
Now, let's put down an even number of odd numbers to work with,and see
what we can notice about them:
1, 3, 5, 7, 9, 11, 13, 15 .
Number of items in the set . . . 8
Sum of all the items in the set . . . 64
Hmmm. That's interesting. 64 happens to be the square of 8 .
Do you think that might be all there is to it ?
Let's check it out:
Even-numbered lists of odd numbers:
1, 3 Items = 2, Sum = 4
1, 3, 5, 7 Items = 4, Sum = 16
1, 3, 5, 7, 9, 11 Items = 6, Sum = 36
1, 3, 5, 7, 9, 11, 13, 15 . . Items = 8, Sum = 64 .
Amazing ! The sum is always the square of the number of items in the set !
For a sum of 400 ... which just happens to be the square of 20,
we just need the <em><u>first 20 consecutive odd numbers</u></em>.
I slogged through it on my calculator, and it's true.
I never knew this before. It seems to be something valuable
to keep in my tool-box (and cherish always).
Answer: 
Step-by-step explanation:
<u>Given expression</u>
4x³ + 24x² - 288x
<u>Factorize 4x out from the expression</u>
4x · x² + 4x · 6x - 4x · 72
4x (x² + 6x - 72)
<u>Cross multiply to factorize the remaining polynomial expression</u>
<em>The meaning is to allow the factored product of the constant to add up to the first-degree term</em>
x 12
x -6
<u>Combine the result</u>
Hope this helps!! :)
Please let me know if you have any questions
Answer:
Perimeter =63 inches
Area = 243in²
Step-by-step explanation:
Given data
Length of computer = 18in
Width of computer = 13.5in
From the given data the computer has a rectangular shape
Perimeter of the computer = L+L+W+W= 2L+2W
Perimeter = 2(18)+ 2(13.5)
Perimeter = 36+27=63 inches
Area of rectangular shape = L*W
Area = 18 x 13.5= 243in²
Answer:
Hence, the capacity of the tank when full is 120 cubic m.
Step-by-step explanation:
The measures of water tank is 8m x 5m x 3m.
The capacity of the tank when full is nothing but the capacity of the full tank which is the multiples of given dimensions.
The capacity of the tank when full is,
8m x 5m x 3m = 40 m^2 x 3m
= 120 m^3.
Hence, the capacity of the tank when full is 120 cubic m.
