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Solve the following pair of linear (simultaneous) equation by the method of elimination by substitution: 1.5x + 0.1y = 6.2 3x - 0.4y = 11.2 - Mathematics

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प्रश्न

Solve the following pair of linear (simultaneous) equation by the method of elimination by substitution:

1.5x + 0.1y = 6.2

3x - 0.4y = 11.2

योग
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उत्तर

The given pair of linear equations are

1.5x + 0.1y = 6.2                  ...(1)

3x - 0.4y = 11.2                    ...(2)

equation (1) dividing from 10

`(1.5x)/10 + (0.1"y")/10 = 6.2/10`

⇒ 15x + y = 62 

y = 62 - 15x                 ...(3)

Putting the value of y from in equation (2)

`3x - 0.4(62-15x) = 11.2`

⇒ `(30x-4(62-15x))/10=112/10`   

⇒ 30x - 248 + 60x = 112 

⇒ 90x - 248 = 112

⇒ 90x = 360

⇒ x = 4                   ...(4)

Substitute the value of x from equation (4) in equation (3)

y = 62 - 15x

= 62 - 15(4)     

= 62 - 60

⇒ y = 2 

∴ Solution is x = 4 and y = 2.

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Methods of Solving Simultaneous Linear Equations by Elimination Method
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अध्याय 6: Simultaneous (Linear) Equations (Including Problems) - Exercise 6 (A) [पृष्ठ ७९]

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सेलिना Concise Mathematics [English] Class 9 ICSE
अध्याय 6 Simultaneous (Linear) Equations (Including Problems)
Exercise 6 (A) | Q 8 | पृष्ठ ७९

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