Given that, x – y = 7 Squaring both sides, we get (x – y)2 = (7)2 x2 + y2 – 2xy = 49 Its given that xy = 9, x2 + y2 – 2 (9) = 49 x2 + y2 = 49 + 18 x2 + y2 = 67

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RD Sharma - Mathematics

6. Algebraic Expressions and Identities

1. Rational Numbers
2. Powers
3. Squares and Square Roots
4. Cubes and Cube Roots
5. Playing with Numbers
6. Algebraic Expressions and Identities
7. Factorization
8. Division of Algebraic Expressions
9. Linear Equation in One Variable
10. Direct and Inverse Variable
11. Time and Work
12. Percentage
13. Profit, Loss, Discount and Value Added Tax (VAT)
Compound Interest
15. Understanding Shapes-I (Polygons)
16. Understanding Shapes-II (Quadrilaterals)
17. Understanding Shapes-III (Special Types of Quadrilaterales)
18. Practical Geometry (Constructions)
19. Visualising Shapes
20. Mensuration-I (Area of a Trapezium and a Polygon)
21. Mensuration-II (Volumes and Surface Areas of a Cuboid and a Cube)
22. Mensuration-III (Surface Area and Volume of a Right Circular Cylinder
23. Data Handling-I (Classification Representation of Data as Histograms)
24. Data Handling-II (Graphical Representation of Data as Pie Charts
25. Data Handling-III (Pictorial Representation of Data as Pie Charts
26. Data Handling-IV (Probability)
27. Introduction to Graphs

Exercise 6.1

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Exercise 6.2

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Exercise 6.3

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Exercise 6.4

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Exercise 6.5

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Exercise 6.6

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Exercise 6.7

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Q. 114.0( 9 Votes )

If x- y = 7 and x

Class 8th RD Sharma - Mathematics 6. Algebraic Expressions and Identities

Answer :

Given that, x – y = 7

Squaring both sides, we get

(x – y)² = (7)²

x² + y² – 2xy = 49

Its given that xy = 9,

x² + y² – 2 (9) = 49

x² + y² = 49 + 18

x² + y² = 67

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