Question
A, b, c and d are real positive numbers such that a + b = 5, c + d = 2 and ad = bc = 1. Then ac+bd+(ac) is:
Answer: Option C
:
C
Multiply both equations - (a+b)(c +d) = 10
⟹ ac+bd=8 (ad=bc=1)...(i)
a(c+d)=2a (c+d=2)
⟹ ac+ad=ac+bc=c(a+b)=2a
⟹ac=52...(ii)
Hence (i)+(ii) = ac+bd+(ac) = 8+52=10.5
Was this answer helpful ?
:
C
Multiply both equations - (a+b)(c +d) = 10
⟹ ac+bd=8 (ad=bc=1)...(i)
a(c+d)=2a (c+d=2)
⟹ ac+ad=ac+bc=c(a+b)=2a
⟹ac=52...(ii)
Hence (i)+(ii) = ac+bd+(ac) = 8+52=10.5
Was this answer helpful ?
More Questions on This Topic :
Latest Videos
Latest Test Papers
Submit Solution