SOLUTION: Hi. I'm in grade 7 and i'm not quite sure if this is under the right category but the category I'm talking about is Algebra. I missed a homework handout of Algebra a while ago and

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Question 826654: Hi. I'm in grade 7 and i'm not quite sure if this is under the right category but the category I'm talking about is Algebra. I missed a homework handout of Algebra a while ago and now i forget how to do it. the question I'm stuck on is:
if x,y and z are positive integers with xy=18, xz=3 and yz=6, what is the value of x+y+z?
Answer by ankor@dixie-net.com(22740) (Show Source):
You can put this solution on YOUR website!
if x,y and z are positive integers with xy=18, xz=3 and yz=6,
what is the value of x+y+z?
;
Rearrange the equations and substitute
xy = 18
y =
:
xz = 3
z =
:
yz = 6
replace y with 18/x and replace z with 3/x
* = 6
= 6
54 = 6x^2; multiplied both sides by x^2
= x^2; divided both sides by 6
9 = x^2
x =
x = 3
then
3y = 18
y = 6
and
6z = 6
z = 1
Find x + y + z
3 + 6 + 1 = 10