Question

The sum of a number and 4 times its reciprocal is 13/3
Find both possible numbers.

Answer 1

4/3 or 3

Explanation:

Let, the number be x.

According to the question,

x+4×1/x=13/3

or, x+4/x=13/3

or, x^2+4/x=13/3

or, 3(x^2+4)=13x

or, 3x^2+12=13x

or, 3x^2-13x+12=0

or, 3x^2-(4+9)x+12=0

or, 3x^2-4x-9x+12=0

or, x(3x-4)-3(3x-4)=0

or, (3x-4)(x-3)=0

Either, Or,

3x-4=0 x-3=0

or, 3x=4 .•. x=3

.•. x=4/3

So, the possible numbers are 4/3 or 3.

Answer 2

3 ; 4/3

Explanation:

x + 4(1/x) = 13/3

x + 4/x = 13/3

x^2 -13/3x + 4 = 0

3x^2 - 13x + 12 = 0

Δ = 169 - 144 = 25

x1 = (13 + 5)/6 = 3

x2 = (13-5)/6 = 4/3