Mathematics
Draw the graph of the equation y = 3x - 4. Find graphically
(i) the value of y when x = -1
(ii) the value of x when y = 5.
Answer
Equation :
⇒ y = 3x - 4
When x = 0, y = 3(0) - 4 = 0 - 4 = -4,
x = 2, y = 3(2) - 4 = 6 - 4 = 2,
Table of values :
| x | y |
|---|---|
| 0 | -4 |
| 2 | 2 |
Steps of construction :
Plot the points (0, -4) and (2, 2) on the graph.
Connect the two points by a straight line.
Hence, the graph of the given equation is shown in the adjoining figure.
(i) Steps of construction :
From point, P (x = -1) draw a line parallel to y-axis touching the graph. Mark the point as Q.
From Q draw a line parallel to x-axis, touching y-axis at point R (y = -7).
Hence, y = -7, when x = -1.
(ii) Steps of construction :
From point, S (y = 5) draw a line parallel to x-axis touching the graph. Mark the point as T.
From T draw a line parallel to y-axis, touching x-axis at point U (x = 3).
Hence, x = 3, when y = 5.
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