Answer:
x = -4, y = -2
Step-by-step explanation:
substitute for y
2x - 5(x + 2) = 2
distribute -5
2x -5x - 10 = 2
solve
-3x - 10 = 2
add 10 on both sides
-3x = 12
divide by -3
x = -4
now substitute for x in the equation y = x + 2
y = -4 + 2
y = -2
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:
by adding the circle of area below the doorknob and removing the surface area of the knob itself
Step-by-step explanation:
Answer:
Step-by-step explanation:
94
Mean = add all the numbers up and divide by how many numbers you added
So add (x +120 + 112 + 130 + 128 + 124 ) divided by 6 =118
x is the score you are looking for and 118 is the average he wants
so (x + 614 ) divided by 6 =118
now multiply both sides by 6
x + 614 = 118 times 6
x + 614 = 708
subtract 614 from both sides
x = 94