2y – 5 = 3x + 55. Find the value of x + y.?
回答 (7)
2009-02-17 12:45 pm
✔ 最佳答案
hmmm, you cant work out values for them both from that :S sorry :(
2009-02-17 8:35 pm
You can't determine the value of x+y from that information. It can be any value. Set it equal to 5... solve for x and y. Set it equal to 10... solve for x and y. You can set it equal to anything, and still find an x and y which will make both true.
2009-02-17 11:35 pm
2y - 5 = 3x + 55
3x - 2y = -55 - 5
3x - 2y = -60
3x - 2y = -60
3x = 2y - 60
x = (2y - 60)/3
x = 2y/3 - 20
3x - 2y = -60
2y = 3x - (-60)
y = (3x + 60)/2
y = 3x/2 + 30
x + y
= (2y/3 - 20) + (3x/2 + 30)
= 2y/3 - 20 + 3x/2 + 30
= 4y/6 + 9x/6 - 20 + 30
= (4y + 9x)/6 + 10
3x - 2y = -55 - 5
3x - 2y = -60
3x - 2y = -60
3x = 2y - 60
x = (2y - 60)/3
x = 2y/3 - 20
3x - 2y = -60
2y = 3x - (-60)
y = (3x + 60)/2
y = 3x/2 + 30
x + y
= (2y/3 - 20) + (3x/2 + 30)
= 2y/3 - 20 + 3x/2 + 30
= 4y/6 + 9x/6 - 20 + 30
= (4y + 9x)/6 + 10
2009-02-17 8:58 pm
Since we only have one equation and two unknowns, we have a dependent system. Number of Equations < Number of Variables==> infinite solutions.
Let's solve for y. ===>2y = 3x + 55 + 5
================>y= (1/2)(3x + 60)
================>y = (3/2)(x+ 20)
The solution is dependent on either x or y.
The parametric form of the solution is the point (t, (3/2(t+20)) valid for all t, where t is a real number.
The value x + y is t + 3/2(t + 20) = 2t/2 +3t/2 + 30
===>x + y =5t/2 + 30 for all t, where t is a real number.
Let's solve for y. ===>2y = 3x + 55 + 5
================>y= (1/2)(3x + 60)
================>y = (3/2)(x+ 20)
The solution is dependent on either x or y.
The parametric form of the solution is the point (t, (3/2(t+20)) valid for all t, where t is a real number.
The value x + y is t + 3/2(t + 20) = 2t/2 +3t/2 + 30
===>x + y =5t/2 + 30 for all t, where t is a real number.
2009-02-17 8:39 pm
Y=(3x+55+5)\2
=3(x+20)\2
x+y= x+3(x+20)\2
=(5x+60)\2
=5\2(x+60)
=3(x+20)\2
x+y= x+3(x+20)\2
=(5x+60)\2
=5\2(x+60)
2009-02-17 8:38 pm
I work it out that x + y = 2.5x + 30 = 1.66667y - 20
2009-02-17 8:36 pm
2y - 5 = 3x +55
2y = 3x + 60
y = 1.5x + 60
2y = 3x + 60
3x = 2y - 60
x = (2/3)y - 20
y + x = 1.5x + 60 + (2/3)y - 20
y + x = 1.5x + (2/3)y + 40
2y = 3x + 60
y = 1.5x + 60
2y = 3x + 60
3x = 2y - 60
x = (2/3)y - 20
y + x = 1.5x + 60 + (2/3)y - 20
y + x = 1.5x + (2/3)y + 40
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