If f(x) = log10 (1 + x), then what is 4f(4) + 5f(1) – log10 2 equal to?

If f(x) = log10 (1 + x), then what is 4f(4) + 5f(1) – log10 2 equal to? Correct Answer 4

Calculation:

Given: f(x) = log10 (1 + x)

⇒ f(4) = log10 (5)

⇒ f(1) = log10 (2)

⇒ 4f(4) + 5f(1) – log10 2 = log10 625 + log10 32 - log10 2

⇒ 4f(4) + 5f(1) – log10 2 = log10 (625 × 32) - log10 2

⇒ 4f(4) + 5f(1) – log10 2 = log10 (2 × 104) - log10 2

⇒ 4f(4) + 5f(1) – log10 2 = log10 2 + 4 log10 10 - log10 2

⇒ 4f(4) + 5f(1) – log10 2 = 4

Related Questions

If log4 (5) = log6 (5 + x3) then which if following is true if log10 5 ≈ 0.69 and log10 4 ≈ 0.60
If log5 (6) = log7 (7 + x2 + 2x) then which of the following is true. Given log10 (6) ≈ 0.77, log10 (5) ≈ 0.69