2017 · Q29
The values of x which satisfy the equation 5¹⁺ˣ+5¹⁻ˣ=26 are
Elementary MathematicsAlgebra
- A-1,1
- B0,1
- C1,2
- D-1,0
Explanation
Put y = 5ˣ: 5y + 5/y = 26 gives 5y² − 26y + 5 = 0, i.e. (5y−1)(y−5) = 0. So y = 5 or 1/5, giving x = 1 or x = −1: option A.