CBSE Class 10 Answered

Q.  Solve the following equations either by substitution or by elimination method:

1.    1/2(x+2y) + 5/3(3x-2y) = -3/2

       5/4(x+2y) - 3/5(3x-2y) = 61/60

2.    7x-2y/xy = 5

      8x+7y/xy = 15

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We'll solve 2.

(7x - 2y)/xy = 5

(8x + 7y)/xy = 15

8x + 7y = 15xy   ... (2)

Multiply (1) by 8 and divide by 7,

8x - 16y/7 = 40xy/7  ... (3)

Subtract this from (2),

(7 + 16/7)y = (15 - 40/7)xy

65y/7 = 65xy/7

i.e. x = 1,

Using this value in (1)

7 -  2y = 5y

y = 1

Regards,

Team,

TopperLearning.

7x - 2y = 5xy  .... (1)