Math Problem Statement

What is f(a+b) if f(x) = 3x^2 - 2x + 5? What is f(-3/5) if f(x) = x^3 - 3x^2 + x - 5? What is f(3) if f(x) = 4x^5 - x^3 + 5x^2 + 3x/2 - 1/2?

Solution

Let's solve each problem one by one from the image you've uploaded:

Problem 4:

We are given f(x)=3x22x+5f(x) = 3x^2 - 2x + 5. The goal is to find f(a+b)f(a+b).

  1. Substitute a+ba+b into the function for xx: f(a+b)=3(a+b)22(a+b)+5f(a+b) = 3(a+b)^2 - 2(a+b) + 5
  2. Expand the expression: (a+b)2=a2+2ab+b2(a+b)^2 = a^2 + 2ab + b^2 So, we get: f(a+b)=3(a2+2ab+b2)2(a+b)+5f(a+b) = 3(a^2 + 2ab + b^2) - 2(a + b) + 5
  3. Distribute the constants: f(a+b)=3a2+6ab+3b22a2b+5f(a+b) = 3a^2 + 6ab + 3b^2 - 2a - 2b + 5 Thus, the final expression for f(a+b)f(a+b) is: f(a+b)=3a2+6ab+3b22a2b+5f(a+b) = 3a^2 + 6ab + 3b^2 - 2a - 2b + 5

Problem 5:

We are given f(x)=x33x2+x5f(x) = x^3 - 3x^2 + x - 5 and asked to find f(35)f\left( -\frac{3}{5} \right).

  1. Substitute x=35x = -\frac{3}{5} into the function: f(35)=(35)33(35)2+(35)5f\left( -\frac{3}{5} \right) = \left( -\frac{3}{5} \right)^3 - 3\left( -\frac{3}{5} \right)^2 + \left( -\frac{3}{5} \right) - 5
  2. Calculate each term: (35)3=27125\left( -\frac{3}{5} \right)^3 = -\frac{27}{125} (35)2=925,3(925)=2725\left( -\frac{3}{5} \right)^2 = \frac{9}{25}, \quad 3\left( \frac{9}{25} \right) = \frac{27}{25} (35)=35\left( -\frac{3}{5} \right) = -\frac{3}{5}
  3. Combine the terms: f(35)=271252725355f\left( -\frac{3}{5} \right) = -\frac{27}{125} - \frac{27}{25} - \frac{3}{5} - 5
  4. Convert all terms to a common denominator (125): f(35)=2712513512575125625125f\left( -\frac{3}{5} \right) = -\frac{27}{125} - \frac{135}{125} - \frac{75}{125} - \frac{625}{125}
  5. Combine the fractions: f(35)=2713575625125=862125f\left( -\frac{3}{5} \right) = \frac{-27 - 135 - 75 - 625}{125} = \frac{-862}{125} Thus, the result is: f(35)=862125f\left( -\frac{3}{5} \right) = -\frac{862}{125}

Problem 6:

We are given f(x)=4x5x3+5x2+3x212f(x) = 4x^5 - x^3 + 5x^2 + \frac{3x}{2} - \frac{1}{2} and asked to find f(3)f(3).

  1. Substitute x=3x = 3 into the function: f(3)=4(3)5(3)3+5(3)2+3(3)212f(3) = 4(3)^5 - (3)^3 + 5(3)^2 + \frac{3(3)}{2} - \frac{1}{2}
  2. Calculate each term: 35=243,4(243)=9723^5 = 243, \quad 4(243) = 972 33=273^3 = 27 32=9,5(9)=453^2 = 9, \quad 5(9) = 45 3(3)2=92\frac{3(3)}{2} = \frac{9}{2} 12=12\frac{1}{2} = \frac{1}{2}
  3. Combine the terms: f(3)=97227+45+9212f(3) = 972 - 27 + 45 + \frac{9}{2} - \frac{1}{2} f(3)=99027+82f(3) = 990 - 27 + \frac{8}{2} f(3)=963+4=967f(3) = 963 + 4 = 967 Thus, the result is: f(3)=967f(3) = 967

Would you like more details on any of the solutions? Here are 5 related questions:

  1. How can we apply function transformations to evaluate values like f(a+b)f(a+b) for more complex functions?
  2. What steps can be taken to simplify polynomial functions further?
  3. How do we handle fractional exponents in polynomial evaluation?
  4. What are the general methods for solving polynomials with multiple variables?
  5. How does substitution work in higher-degree polynomials?

Tip: Always check your calculations step-by-step, especially when dealing with fractional powers or combining terms from different denominators.

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Math Problem Analysis

Mathematical Concepts

Algebra
Polynomial Functions
Substitution

Formulas

f(a+b) = 3a^2 + 6ab + 3b^2 - 2a - 2b + 5
f(-3/5) = -862/125
f(3) = 967

Theorems

Substitution of values in polynomial functions
Expansion of quadratic terms

Suitable Grade Level

Grades 10-12