Answer:
20
Step-by-step explanation:
Givens
Let child one = x
Let child two = y
Let child three = z
Equations
x^2 + y^2 + z^2 = 100
xy + xz + yz = 150
Solution
There's a trick here. The square of their weights added together is equal (with some modification) to the given conditions. Start by squaring (x+y+z).
(x + y + z)^2 = x^2 + y^2 + z^2 + 2xy + 2xz + 2yz
Take out 2 as a common factor from the last three terms.
(x + y + z)^2 = (x^2 + y^2 + z^2+ 2(xy + xz + yz) )
Substitute the given conditions into the equation. (x^2 + y^2 + z^2) = 100 and 2*(xy + xz + yz) = 2 * 150
(x + y + z)^2 = 100 + 2*150
(x + y + z)^2 = 100 + 300
(x + y + z)^2 = 400
Take the square root of both sides.
sqrt(x+y+z)^2 = sqrt(400)
x + y + z = 20
Note
This answer tells you nothing about the values of x y and z. On the other hand it does not ask for the values of x y and z.
Answer:
B, C
Step-by-step explanation:
A: √4 = 2, so the side lengths form an equilateral triangle, not a right triangle.
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B: √(9²+40²) = 41 . . . . these form a right triangle
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C: √(5² +10²) = √125 . . . . these form a right triangle
Answer:
22 1/2
Step-by-step explanation:
6×3 3/4=22 1/2
Answer:
y = 3 + 12x - - - (1)
y = 9 + 10x - - - (2)
3 albums
$39
Step-by-step explanation:
Let number of download = x
Given :
I-moon :
Initial joining fee = $3
Cost per download = $12
Hence,
y = 3 + 12x - - - (1)
I - Toons :
Initial joining fee = $9
Cost per download = $10
y = 9 + 10x - - - (2)
For cost to be the same ;
Equate (1) and (2)
3 + 12x = 9 + 10x
Collect like terms
3 - 9 = 10x - 12x
-6 = - 2x
x = 3
It will take 3 albums
Cost :
3 + 12(3)
3 + 36 = 39
