Math Problem Statement

If f left parenthesis x right parenthesis equals 2 x cubed plus Ax squared plus 7 x minus 7 and f left parenthesis 2 right parenthesis equals 7​, what is the value of​ A?

Solution

We are given the function:

f(x)=2x3+Ax2+7x7f(x) = 2x^3 + Ax^2 + 7x - 7

And we know that:

f(2)=7f(2) = 7

Substitute x=2x = 2 into the function:

f(2)=2(2)3+A(2)2+7(2)7f(2) = 2(2)^3 + A(2)^2 + 7(2) - 7

Simplify the expression:

f(2)=2(8)+A(4)+147f(2) = 2(8) + A(4) + 14 - 7

f(2)=16+4A+147f(2) = 16 + 4A + 14 - 7

f(2)=23+4Af(2) = 23 + 4A

We are told that f(2)=7f(2) = 7, so:

23+4A=723 + 4A = 7

Solve for AA:

4A=7234A = 7 - 23

4A=164A = -16

A=164=4A = \frac{-16}{4} = -4

Thus, the value of AA is 4-4.

Would you like more details or have any questions?

Here are 5 related questions:

  1. How do you solve cubic equations in general?
  2. What are other ways to find coefficients in a polynomial?
  3. How would you approach solving a system of equations involving multiple variables?
  4. What happens when a function’s value is undefined for a given xx?
  5. How do the coefficients of a polynomial affect its graph?

Tip: When solving equations, always simplify expressions step by step to avoid errors.

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Math Problem Analysis

Mathematical Concepts

Algebra
Polynomial Functions
Substitution Method

Formulas

f(x) = ax^3 + bx^2 + cx + d
Substitution to find the value of a coefficient

Theorems

Basic properties of polynomials

Suitable Grade Level

Grades 9-11