31) A function is defined for all positive numbers \( x \) as \( f(x)=a \sqrt{x}+b \). What is the value of \( f(3) \), if f(4) \( -f(1)=2 \) and \( f(4)+f(1)=10 \) ? (A) 1 (B) 2 (C) \( 2 \sqrt{3} \) (D) \( 2 \sqrt{3}+2 \) 32)
Real Tutor Solution
Answer
Solution
Reviewed and approved by the UpStudy tutoring team
Bonus Knowledge
To solve for \(f(3)\), let's first express \(f(4)\) and \(f(1)\) using the function definition \(f(x) = a \sqrt{x} + b\). From the equations provided: 1. \(f(4) - f(1) = 2\) 2. \(f(4) + f(1) = 10\) We can substitute the function definition into these equations: 1. \(a \sqrt{4} + b - (a \sqrt{1} + b) = 2 \implies 2a + b - (a + b) = 2 \implies a = 2\) 2. Replacing \(a\) in the second equation: \(2 \sqrt{4} + b + (2 + b) = 10 \implies 4 + b + 2 + b = 10 \implies 2b + 6 = 10 \implies 2b = 4 \implies b = 2\) Now that we have \(a = 2\) and \(b = 2\), we can find \(f(3)\): \[ f(3) = a \sqrt{3} + b = 2\sqrt{3} + 2 \] Thus, the value of \(f(3)\) is \(2\sqrt{3} + 2\). So the answer is: (D) \( 2 \sqrt{3}+2 \)