This question is taken from linear equations in two variables in which we have to find the value of variables x and y from the equations 4x+6y=3xy, 8x+9y=5xy
Kindly give me a detailed solution of this question
RS Aggarwal, Class 10, chapter 3B, question no 25
The given equations are:
4x + 6y = 3xy …..(i)
8x + 9y = 5xy ……(ii)
From equation (i), we have:
4x + 6y/ xy = 3
⇒ 4/y + 6/x = 3 ……(iii)
For equation (ii), we have:
8x + 9y/ xy = 5
⇒ 8/y + 9/x = 5 ……(iv)
On substituting 1/y = v and 1/x = u, we get:
4v + 6u = 3 ……(v)
8v + 9u = 5 …….(vi)
On multiplying (v) by 9 and (vi) by 6, we get:
36v + 54u = 27 ….(vii)
48v + 54u = 30 ….(viii)
On subtracting (vii) from (viii), we get:
12v = 3
⇒ v = 3/12 = 1/4
⇒ 1/ y = 1/4
⇒ y = 4 On substituting y =4 in (iii), we get:
4/4 + 6/x= 3
⇒ 1 + 6/x = 3
⇒ 6/x = (3 – 1) = 2
⇒ 2x = 6
⇒ x = 6/2 = 3
Hence, the required solution is x = 3 and y = 4.