Answer:
5ohms and 20ohms
Explanation:
Let the resistance of each wire be R1 and R2, if the equivalent resistance in series is 25 ohms, then;
R1 + R2 = 25 ...1
If the equivalent in parallel is 4 ohm, then;
1/R1 + 1/R2 = 1/4
R2+R1/R1R2 = 1/4
Cross multiply
4(R2+R1) = R1R2 ...2
From 1;
R1 = 25 - R2 ... 3
Substitute 3 into 2
4(R2+25-R2) = (25-R2)R2
4(25) = (25-R2)R2
100 = 25R2 - R2²
R₂² -25R₂+100 = 0
R₂² -20R₂-5R₂+100 = 0
R₂(R₂-20)-5(R₂-20) = 0
(R₂-5)(R₂-20)=0
R₂ = 5 or 20
Since R₁ = 25-R₂
R₁ = 25 - 5
R₁ = 20
Hence the resistances are 5ohms and 20ohms
