Manipal MET2013MathematicsBinomial Theorem
The value of x in the expression (x+x^ ₁₀ x )^0 , if the third term in the expansion is 1,000,000 , is
Options
- A10,10^ -3 / 2
- B100 or 10^ -3 / 2
- C10 or 10^ -5 / 2
- DNone of these
Correct answer
C. 10 or 10^ -5 / 2
Step-by-step solution
x is defined only when x 0 Now, the 3^ rd term in the expansion T_ 2+1 = ^5 C₂ x⁵⁻² (x^ 00₁₀ x )^2=1,000,000 (given) x^ 3+2 ₁₀ x =10^5 . Taking logarithm of both sides, we get aligned & (3+2 ₁₀ x ) ₁₀ x aligned =5 2 y^2+3 y-5=0 where ₁₀ x=y array lc & (y-1)(2 y+5)=0 & y=1 or -5 / 2 & ₁₀ x=1 or -5 / 2 & x=10^1=10 or 10^ -5 / 2 array