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Solve the following pair of linear equations by the substitution and cross-multiplication methods 8x + 5y = 9 , 3x + 2y = 4 - CBSE Class 10 - Mathematics

ConceptAlgebraic Methods of Solving a Pair of Linear Equations Cross - Multiplication Method

Question

Solve the following pair of linear equations by the substitution and cross-multiplication methods

8x + 5y = 9

3x + 2y = 4

Solution

8x +5y = 9 ... (i)

3x +2y = 4 ... (ii)

From equation (ii), we get

x = (4-2y)/3 ... (iii)

Putting this value in equation (i), we get

8((4-2y)/3) + 5y = 9

32 - 16y +15y = 27

-y = -5

y = 5 ... (iv)

Putting this value in equation (ii), we get

3x + 10 = 4

x = -2

Hence, x = -2, y = 5

By cross multiplication again, we get

8x + 5y -9 = 0

3x + 2y - 4 = 0

x/(-20-(-18)) = y/(-27-(-32)) = 1/(16-15)

x/-2 = y/5 = 1/1

x/-2 = 1 and y/5 = 1

x = -2 and y = 5

Is there an error in this question or solution?

APPEARS IN

NCERT Solution for Mathematics Textbook for Class 10 (2019 to Current)
Chapter 3: Pair of Linear Equations in Two Variables
Ex. 3.50 | Q: 3 | Page no. 62

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Solution Solve the following pair of linear equations by the substitution and cross-multiplication methods 8x + 5y = 9 , 3x + 2y = 4 Concept: Algebraic Methods of Solving a Pair of Linear Equations - Cross - Multiplication Method.
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