Question

2a-b=9 ; a+b=3 this is the simultaneous equation of 10th std please answers this question

Answer 1

2 a - b = 9.......... (1)
a + b =3.......... (2)

2 a - b = 9
2 a = 9 + b
a =( 9+b ) /2
Substituting a = ( 9 + b ) / 2 in second equation we get:
( 9+ b) / 2 + b = 3
=> (9 + b + 2b ) / 2 = 3
=> 9 + 3b = 3 × 2
=> 9 + 3b = 6
=> 3b = 6 - 9
=> 3b = -3
=> b = -3 / 3
=> b = -1

Substituting b = -1 in equation 1 we get:
2a - (-1) = 9
=> 2a + 1 = 9
=> 2a = 9 - 1
=> 2a = 8
=> a = 8 / 2
=> a = 4

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