WHERE IS the point R
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WHERE IS the point R

[From: ] [author: ] [Date: 11-10-08] [Hit: ]
the use the first equation to find y.You should get x=1.7 and y=0.Another way would be to draw graphs for both lines.-Y = 2X -3 and 3Y + 4X = 8 are two lines which intersect at point R.Y = 2X - 3 .......
The line y=2x-3 meets the x-axis at the point P, and the line 3y+4x=8 meets the x-axis at the point Q. The two lines intersect at the point R.

find the coordinates of R

i really dont know how to do this

please show me how to do it

thank you

-
You need to solve the two equations together

One way to do this is to use the first equation in the second:

y=2x-3
3y+4x=8

so

3(2x-3) + 4x = 8

You now need to expand the brackets and do some algebra to find the x co-ordinate of R, the use the first equation to find y.

You should get x=1.7 and y=0.4

Another way would be to draw graphs for both lines.

-
Y = 2X -3 and 3Y + 4X = 8 are two lines which intersect at point R.
Let's rewrite the two equations as Y = something

Y = 2X - 3 ..................first line equation unchanged (equation 1)
Y = ( 8 - 4X)/3 ...........subtracted 4X from both sides and divided both sides by 3 (equation 2)

If the lines intersect this means that at the point of intersection both lines are equal i.e. the point of intersection lies on both lines. This means that:

2X - 3 = (8 - 4X)/3 ......make the two lines equal

6X - 9 = 8 - 4X ...........multiply both sides of the equation above by 3
10X = 17 ............put the Xs on one side and the constants on the other
X = 17/10
We now find Y
from the equation of the first line we have:

Y = 2*17/10 - 3 = (34 -30)/10 = 4/10 = 2/5
from equation 2

Y = (8 - 4*17/10)/3 = (8 - 2*17/5)/3 = (40 - 34)/15 = 6/15 = 2/5

so the point of intersection is (17/10, 2/5)

-
y = 2x - 3
y = (-4x+8)/3

the lines intercepts when y1=y2 and x1=x2

2x - 3 = -4/3 x + 8/3

2x + 4/3 x = 3 + 8/3

6x + 4x = 9 + 8
10x = 17
x= 17/10

x= 1.7
y= 2(1.7)-3
y= 0.4
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