w+x+y+z=81
5x=w
5y=x
2y=z
what does x equal???
2007-01-17 08:39:02 · 7 answers · asked by LazyDaisy 3 in Science & Mathematics ➔ Mathematics
I got 14.464 and thats wrong apparently, the answer is supposed to be 5. how does that work?
2007-01-17 08:47:48 · update #1
If you check your work, only x=5 works. It's so confusing.
2007-01-17 08:53:12 · update #2
BTW it was from another question, i tried it but it didn't work in the equation, is the equation wrong, am i not supposed to solve it mathematiclly
http://answers.yahoo.com/question/index;_ylt=AuXG_UwqDIds1l1zPCfjxl0Cxgt.?qid=20070117132021AAOBzwO
2007-01-17 09:02:15 · update #3
y=x/5
z=2y=2x/5
5x+x+x/5+2x/5=81
6x+3x/5=81
33x/5=81
x=135/11 = 12 3/11
2007-01-17 08:45:13 · answer #1 · answered by Anonymous · 1⤊ 0⤋
w + x + y + z = 81
5x = w
5y = x
2y = z
All you have to do is take all the variables and express them in terms of x.
5x = w.
5y = x implies y = (1/5)x
2y = z, but since we solved for y being 1/5 x, it follows that
2(1/5)x = z, or z = (2/5)x
w + x + y + z = 81, so now replacing every variable which are now in terms of x,
5x + x + (1/5)x + (2/5)x = 81
Simplify,
6x + (1/5)x + (2/5)x = 81
Multiply both sides by 5 to get rid of all fractions.
30x + x + 2x = 405
Simplify,
33x = 405
x = 405/33 = 135/11
2007-01-17 16:47:27 · answer #2 · answered by Puggy 7 · 2⤊ 0⤋
Substitute w=5x, y=x/5, and z=2x/5 into the original equation,
x(5 + 1 + 1/5 + 2/5) = 81
Solve for x,
x = 12 3/11 = 12.273
2007-01-17 16:46:28 · answer #3 · answered by sahsjing 7 · 1⤊ 0⤋
try to stay w/ 1 variable at first. It seems like y is a good choice to use:
we know that x = 5y, so sub that into the first equation:
w + 5y + y + z = 81. And z = 2y, so, sub 2y into z,
w + 5y + y + 2y = 81. Now, it get a little tricky here; however, we know that w = 5x, and x = 5y, sub 5y into where x is on the w=5x
w = 5 * (5y) = 25y, and then sub this into the 1st equation,
25y + 5y + y + 2y = 81, and simplify
33y = 81 therefore, y = 81/33. From here, we already know that
x = 5y, and y = 81/33, so
x = 5 (81/33) = 405/33 or 12. 272727
2007-01-17 16:49:04 · answer #4 · answered by Cu Den 2 · 1⤊ 0⤋
w+x+y+z=81
5x=w
5y=x -> y=1/5 x
2y=z -> z=2y = 2/5 x
Thus:
5x+x+1/5x+2/5x=6 3/5 x = 81
thus x=135/11
2007-01-17 16:47:51 · answer #5 · answered by Anonymous · 1⤊ 1⤋
First, you need to substitute the given values into the equation. You should get the equation 5x + x + y + 2y = 81. Now you've narrowed it down to 2 variables. Now you substitute again, leaving you with 5x + x + x/5 + 2x/5 = 81. 6x + 3x/5 = 81. 5(6x + 3x/5) = 5(81). 30x + 15x = 405. 45x = 405. x = 9.
2007-01-17 16:49:38 · answer #6 · answered by stephieSD 7 · 1⤊ 1⤋
w + x + y + z = 81
replace w with 5x (Since, 5x=w)
5x + x + y + z = 81
6x + y + z = 81
Now replace x with 5y (5y=x)
6*(5y) + y + z = 81
31y + z = 81
Now replace z with 2y (2y=z)
31y + 2y = 81
33y = 81
y = 81 / 33
or
y = 27/11
But we know from above that 5y = x
therefore, x = 5* (27/11)
so, x = 12 3/11 = 12.272727...
2007-01-17 16:49:23 · answer #7 · answered by susrsu 2 · 1⤊ 0⤋