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If-1-R-1-R-1-1-R-2-R-1-R-2-gt-0-and-R-1-R-2-C-Constant-then-prove-that-R-will-be-maximum-when-R-1-R-2-




Question Number 208215 by MATHEMATICSAM last updated on 07/Jun/24
If (1/R) = (1/R_1 ) + (1/R_2 ) [R_1 , R_2  > 0] and   R_1  + R_2  = C (Constant) then prove that  R will be maximum when R_1  = R_2 .
If1R=1R1+1R2[R1,R2>0]andR1+R2=C(Constant)thenprovethatRwillbemaximumwhenR1=R2.
Answered by mr W last updated on 07/Jun/24
(1/R)=(1/R_1 )+(1/R_2 )=((R_1 +R_2 )/(R_1 R_2 ))=(C/(R_1 R_2 ))  R=((R_1 R_2 )/C)=((((√(R_1 R_2 )))^2 )/C)≤(1/C)(((R_1 +R_2 )/2))^2 =(C/4)  R_(max) =(C/4)  Equality when R_1 =R_2
1R=1R1+1R2=R1+R2R1R2=CR1R2R=R1R2C=(R1R2)2C1C(R1+R22)2=C4Rmax=C4EqualitywhenR1=R2
Answered by zamin2001 last updated on 07/Jun/24
(1/R)=(1/R_1 )+(1/R_2 )⇒R=((R_1 ×R_2 )/(R_1 +R_2 ))  & R_1 +R_2 =C &R_2 =C−R_1   ⇒ R=((R_1 ×(C−R_1 ))/C)=R_1 −(1/C)R_1 ^2 ⇒R^′ =1−(2/C)R_1   ⇒^(R′=0)  1−(2/C)R_1 =0⇒ R_1 =(C/2) & R_2 =C−R_1 =C−(C/2)=(C/2)  ⇒ R_1 =R_2
1R=1R1+1R2R=R1×R2R1+R2&R1+R2=C&R2=CR1R=R1×(CR1)C=R11CR12R=12CR1R=012CR1=0R1=C2&R2=CR1=CC2=C2R1=R2

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