A) 2. 5
B) 5, 8
C) 4, 8
D) 3, 6
Correct Answer: C
Solution :
Given equations are \[2x+3y=7\]and \[2ax+(a+b)\,y=28\] For infinitely many solutions, we have \[\frac{2}{2a}=\frac{3}{a+b}=\frac{7}{28}\] Taking first two members, we get \[2a+2b=6a;\] \[\Rightarrow \] \[4a=2b\] \[\Rightarrow \] \[2a=b\] .....(1) Also, \[\frac{2}{2a}=\frac{7}{28}\] \[\Rightarrow \] \[a=4\] From (1) and (2), we have \[2(4)=b\,\,\Rightarrow \,\,\,b=8\]You need to login to perform this action.
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