Tamil Nadu Board of Secondary EducationSSLC (English Medium) Class 10th
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Draw the graph of y = x2 + 3x – 4 and hence use it to solve x2 + 3x – 4 = 0 - Mathematics

Graph
Sum

Draw the graph of y = x2 + 3x – 4 and hence use it to solve x2 + 3x – 4 = 0

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Solution

Let y = x2 + 3x – 4

(i) Draw the graph of y = x2 + 3x – 4

x – 5 – 4 – 3 – 2 – 1 0 1 2 3 4
x2 25 16 9 4 1 0 1 4 9 16
3x –15 – 12 – 9 – 6 – 3 0 3 6 9 12
– 4 – 4 – 4 – 4 – 4 – 4 – 4 – 4 – 4 – 4 – 4
y 6 0 – 4 – 6 – 6 – 4 0 6 14 24

(ii) Plot the points (– 5, 6), (– 4, 0), (– 3, – 4), (– 2, – 6), (– 1, – 6), (0, – 4), (1, 0), (2, 6), (3, 14) on the graph using suitable scale.

(iii) Join the points by a free hand smooth curve.

The smooth curve is the graph of y = x2 – 4x + 4

(iv) To solve x + 3x – 4 = 0, subtract x2 + 3x – 4 = 0 from y = x2 + 3x – 4.

y = 0

∴ The point of intersection with the x-axis is the solution set.

The solution set is – 4 and 1.

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APPEARS IN

Samacheer Kalvi Mathematics Class 10 SSLC Tamil Nadu State Board
Chapter 3 Algebra
Exercise 3.16 | Q 5 | Page 137
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