Sir please give me a detailed solution of this question as it was already asked in various important examinations in which we have given two equations 1/x+1/y=7, 2/x+3/y=17 and we have to find the value of variables x and y from the given equations by using the method of cross multiplication
RS Aggarwal, Class 10, chapter 3C, question no 9
Simplify given equations:
Let 1/x=u and 1/y=v
1/x+1/y=7 implies
u+v=7
2/x+3/y=17 implies
2u+3v=17
New set of equation is:
u+v=7...(1)
2u+3v=17...(2)
From equation (1):a1=1,b1=1 and c1=−7
From equation (2):a2=2,b2=3 and c2=−17
Using cross multiplication method:
u/(−17+21)=v/(−14+17)=1/(3−2)
u/4=1 and v/3=1
u=4 and q=3
x=1/4 nad y=1/3 [Since we consider p=1/x and q=1/y]
Answer x=1/4,y=1/3