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Draw the Graph of the Equation 2x - 3y - 5 = 0 from the Graph, Find: X1, the Value of X, When Y = 7 - Mathematics

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Question

Draw the graph of the equation 2x - 3y - 5 = 0
From the graph, find:
(i) x1, the value of x, when y = 7
(ii) x2, the value of x, when y = - 5.

Graph
Sum

Solution

2x - 3y - 5 = 0
⇒ 2x = 3y + 5
⇒ x = `(3y + 5)/(2)`

When y = 1,
x = `(3(1)+5)/(2)`
= `(8)/(2)`
= 4

When y = 3,
x = `(3(3)+5)/(2)`
= `(9 + 5)/(2)`
= 7

When y = - 1,
x = `(3(-1)+5)/(2)`
= `(5 - 3)/(2)`
= 1

X 4 7 1
Y 1 3 - 1

Plotting these points we get the required graph as shown below:

(i) The value of x, when y = 7:

We have the equation of the line as 

x = `(3y + 5)/(2)`

Now substitute y = 7 and x = x1:
x1 = `(3(7) + 5)/(2)`

= `(21 + 5)/(2)`

= `(26)/(2)`
= 13

(ii) The value of x, when y = - 5:

Now substitute y = - 5 and x = x2

x2 = `(3(-5) + 5)/(2)`

= `(-15 + 5)/(2)`

= `(-10)/(2)`

 = -5.

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Chapter 27: Graphical Solution (Solution of Simultaneous Linear Equations, Graphically) - Exercise 27 (A) [Page 326]

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Selina Concise Mathematics [English] Class 9 ICSE
Chapter 27 Graphical Solution (Solution of Simultaneous Linear Equations, Graphically)
Exercise 27 (A) | Q 4 | Page 326
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