20x+20y=270----(1)
20x-40y=0------(2)
---------------------------
60y=270.
y=270/60.
y=4.5.
ttherefore x=9..........!!!!!!!!!
done. Now it is crct..
Maths problem (15 points)
Sort:
How many points I will get?
Everytime u tell that with questions.
ajay, not quite right, re-read your calculations, you made a mistake.
By substitution
20x=40y
x=2y.
x+y=13.5
3y = 13.5
y=13.5/3=4.5
x=9.........
Right na??
your "y" is correct, try again on x.
huss! How many points I will get now??
chessman_calum wrote:
Using substitution solve the following simultaneous equation:
20x - 40y = 0
x + y = 13.5
You must show all your working.
20x-40y=0 [Equation...(1)]
20x+20y=270 [Multiplying equation...(2) by 20]
By substraction, -60y=-270
This implies y=27/6=4.5 and x=13.5-4.5=9
i dont think may people understand the concept of "substitution"
20x - 40y = 0 (I)
x + y = 13.5 (II)
Isolating x in II:
x + y = 13.5 --> x = 13.5 - y
Replacing x in I:
20(13.5 - y) - 40y = 0 --> 270 - 20y - 40y = 0 --> 60y = 270 --> y = 4.5
Replacing y in II:
x + 4.5 = 13.5 --> x = 9
Therefore, the solution to the system is S{(9, 4.5)}
DraeKlae has got the concept of substitution, replacing x or y from a linear equation to a quadradtric. Well done.
20x - 40y = 0
=> 20x = 40y
=> x = 2y ---(1)
x + y = 13.5
=> (2y) + y = 13.5 (substituting x as 2y)
=> y = 13.5/3 = 4.5
Final Ans :
x = 9; y = 4.5
20x - 40y = 0
Therefore 20x=40y
x=2y
Replacing x=2y in x+y=13.5
2y+y=13.5
3y=13.5
y=4.5
x=2y=9
x=9, y=4.5
All correct. Well done.
the problem has been already solved? missed to score????
I think DraeKlae and Ajay-The_grandmaster deserve 7.5 points each.
chessman_calum wrote:
Using substitution solve the following simultaneous equation:
20x - 40y = 0
x + y = 13.5
You must show all your working.
20x-40y=0
=>20x=40y
=>x=2y
x+y=13.5
=>3y=13.5
=>y=4.5
=>x=9
that isnt substitution.
chessman_calum wrote:
Using substitution solve the following simultaneous equation:
20x - 40y = 0
x + y = 13.5
You must show all your working.
y should we solve it by only substitution when we know easy ways.
Using substitution solve the following simultaneous equation:
20x - 40y = 0
x + y = 13.5
You must show all your working.