Math Problem Statement

01.(FUVEST) Sejam 𝑓(π‘₯) = 2π‘₯ βˆ’ 9 e 𝑔(π‘₯) = π‘₯ 2 + 5π‘₯ + 3. Qual Γ© o valor da soma dos valores absoli (mΓ³dulo) das raΓ­zes da equaΓ§Γ£o 𝑓(𝑔(π‘₯)) = 𝑔(π‘₯)? 02.(GV) Sejam 𝑓 e 𝑔 duas funΓ§Γ΅es de R em R, tais que 𝑓(π‘₯) = 2π‘₯ e 𝑔(π‘₯) = 2 βˆ’ π‘₯. Qual Γ© o valor de x na equaΓ§Γ£o 𝑓(𝑔(π‘₯)) + 𝑔(𝑓(π‘₯)) = 𝑓(𝑓(π‘₯)) + 𝑔(𝑔(π‘₯)). 03.(MACK) As funΓ§Γ΅es 𝑓(π‘₯) = 3 βˆ’ 4π‘₯ e 𝑔(π‘₯) = 3π‘₯ + π‘š, onde π‘š Γ© uma constante, sΓ£o tais que 𝑓(𝑔(π‘₯)) = 𝑔(𝑓(π‘₯)), qualquer que seja x real. Nessas condiΓ§Γ΅es, qual Γ© o valor da constante π‘š? 04.(MP) Sendo 𝑓(π‘₯) = 2π‘₯2 βˆ’ π‘₯ + 1 e 𝑔(π‘₯) = π‘₯ βˆ’ 2 funΓ§Γ΅es de R em R calcule: a) o valor de π‘“π‘œπ‘”π‘œπ‘“π‘œπ‘”π‘œπ‘”(3). b) os valores reais de x para que se tenha 𝑓(𝑔(π‘₯)) ≀ 2. 𝑔(π‘₯) 05.(ESPM) Considere as funΓ§Γ΅es 𝑓(π‘₯) = π‘™π‘œπ‘”2π‘₯ e 𝑔(π‘₯) = π‘₯ 2 βˆ’ 2π‘₯, definidas para todo x real estritamente positivo. Se π‘Ž > 0 e 𝑓(𝑔(2π‘Ž)) = 3, quanto vale 𝑓(π‘Ž)? 06.(MACK) Sejam as funΓ§Γ΅es 𝑓 e 𝑔 de R em R, definidas por 𝑓(π‘₯) = π‘₯ 2 βˆ’ 4π‘₯ + 10 e 𝑔(π‘₯) = βˆ’5π‘₯ + 20. Qual Γ© o valor da expressΓ£o 𝑦 = (𝑓(4)) 2βˆ’ 𝑔(𝑓(4)) ? 𝑓(0) βˆ’ 𝑔(𝑓(0)) 07.(MACK) Se 𝑓(π‘₯) = βˆšπ‘Ž βˆ’ π‘₯ 2, 𝑔(π‘₯) = βˆšπ‘ βˆ’ π‘₯, e 𝑓(𝑔(2)) = 2, calcule o valor de 𝑓(𝑔(0)). 08.(MP) Para um nΓΊmero real fixo 𝛼, a funΓ§Γ£o 𝑓(π‘₯) = 𝛼. π‘₯ βˆ’ 2 Γ© tal que 𝑓(𝑓(1)) = βˆ’3. Qual Γ© o valor de 𝛼? 09.(ESPM) Considere as funΓ§Γ΅es reais 𝑓(π‘₯) = 2π‘₯ + 1 e 𝑔(π‘₯) = π‘₯ βˆ’ π‘˜, com π‘˜ πœ– R. Podemos afirmar que π‘“π‘œπ‘”(π‘₯) = π‘”π‘œπ‘“(π‘₯) para qualquer x real se o valor de π‘˜ for igual a: a) 0 b) 1 c) 2 d) – 2 e) – 1 10.(ESPM) Na funΓ§Γ£o real 𝑓(π‘₯) = π‘Ž. π‘₯ + 𝑏, com π‘Ž e 𝑏 reais e π‘Ž β‰  0, sabe-se que 𝑓(π‘₯ 2 βˆ’ 1) = 3π‘₯2 βˆ’ 2 para qualquer x real. EntΓ£o, podemos afirmar que: a) π‘Ž + 𝑏 = 5 b) 2π‘Ž βˆ’ 𝑏 = 5 c) π‘Ž βˆ’ 𝑏 = 1 d) π‘Ž βˆ’ 2𝑏 = 0 11.(ESPM) Na funΓ§Γ£o 𝑓(π‘₯) = 2 π‘₯ βˆ’ π‘₯, o valor de π‘“π‘œπ‘“(0) + π‘“π‘œπ‘“(1) + π‘“π‘œπ‘“(2) + π‘“π‘œπ‘“(3) Γ©: a) 28 b) 29 c) 30 d) 31 e) 32 e) π‘Ž + 2𝑏 = 7 12.(MACK) Considere as funΓ§Γ΅es 𝑔(π‘₯) = 4π‘₯ + 5 e h(π‘₯) = 3π‘₯ βˆ’ 2, definidas em R. Um estudante que resolve

Solution

Let's solve the problems step by step:

01. f(x)=2xβˆ’9f(x) = 2x - 9 and g(x)=x2+5x+3g(x) = x^2 + 5x + 3

We need to find the value of the sum of the absolute values of the roots of the equation f(g(x))=g(x)f(g(x)) = g(x).

f(g(x))=2g(x)βˆ’9f(g(x)) = 2g(x) - 9 g(x)=x2+5x+3g(x) = x^2 + 5x + 3

Substituting g(x)g(x) into ff:

f(g(x))=2(x2+5x+3)βˆ’9f(g(x)) = 2(x^2 + 5x + 3) - 9 f(g(x))=2x2+10x+6βˆ’9f(g(x)) = 2x^2 + 10x + 6 - 9 f(g(x))=2x2+10xβˆ’3f(g(x)) = 2x^2 + 10x - 3

Set this equal to g(x)g(x):

2x2+10xβˆ’3=x2+5x+32x^2 + 10x - 3 = x^2 + 5x + 3 x2+5xβˆ’6=0x^2 + 5x - 6 = 0

Solve the quadratic equation:

x=βˆ’5Β±25+242=βˆ’5Β±72x = \frac{-5 \pm \sqrt{25 + 24}}{2} = \frac{-5 \pm 7}{2}

Roots are:

x1=1andx2=βˆ’6x_1 = 1 \quad \text{and} \quad x_2 = -6

Sum of the absolute values of the roots:

∣1∣+βˆ£βˆ’6∣=1+6=7|1| + |-6| = 1 + 6 = 7

02. f(x)=2xf(x) = 2x and g(x)=2βˆ’xg(x) = 2 - x

We need to find xx in the equation f(g(x))+g(f(x))=f(f(x))+g(g(x))f(g(x)) + g(f(x)) = f(f(x)) + g(g(x)).

Calculate each function composition:

f(g(x))=f(2βˆ’x)=2(2βˆ’x)=4βˆ’2xf(g(x)) = f(2 - x) = 2(2 - x) = 4 - 2x g(f(x))=g(2x)=2βˆ’2xg(f(x)) = g(2x) = 2 - 2x f(f(x))=f(2x)=2(2x)=4xf(f(x)) = f(2x) = 2(2x) = 4x g(g(x))=g(2βˆ’x)=2βˆ’(2βˆ’x)=xg(g(x)) = g(2 - x) = 2 - (2 - x) = x

Substitute into the equation:

(4βˆ’2x)+(2βˆ’2x)=4x+x(4 - 2x) + (2 - 2x) = 4x + x 6βˆ’4x=5x6 - 4x = 5x 6=9x6 = 9x x=23x = \frac{2}{3}

03. f(x)=3βˆ’4xf(x) = 3 - 4x and g(x)=3x+mg(x) = 3x + m

We need to find the value of the constant mm such that f(g(x))=g(f(x))f(g(x)) = g(f(x)) for any real xx.

Calculate each function composition:

f(g(x))=f(3x+m)=3βˆ’4(3x+m)=3βˆ’12xβˆ’4mf(g(x)) = f(3x + m) = 3 - 4(3x + m) = 3 - 12x - 4m g(f(x))=g(3βˆ’4x)=3(3βˆ’4x)+m=9βˆ’12x+mg(f(x)) = g(3 - 4x) = 3(3 - 4x) + m = 9 - 12x + m

Equate both compositions:

3βˆ’12xβˆ’4m=9βˆ’12x+m3 - 12x - 4m = 9 - 12x + m 3βˆ’4m=9+m3 - 4m = 9 + m 3βˆ’9=4m+m3 - 9 = 4m + m βˆ’6=5m-6 = 5m m=βˆ’65m = -\frac{6}{5}

04. f(x)=2x2βˆ’x+1f(x) = 2x^2 - x + 1 and g(x)=xβˆ’2g(x) = x - 2

a) Calculate f∘g∘f∘g∘f∘g(3)f \circ g \circ f \circ g \circ f \circ g (3):

g(3)=3βˆ’2=1g(3) = 3 - 2 = 1 f(1)=2(1)2βˆ’1+1=2βˆ’1+1=2f(1) = 2(1)^2 - 1 + 1 = 2 - 1 + 1 = 2 g(2)=2βˆ’2=0g(2) = 2 - 2 = 0 f(0)=2(0)2βˆ’0+1=1f(0) = 2(0)^2 - 0 + 1 = 1 g(1)=1βˆ’2=βˆ’1g(1) = 1 - 2 = -1 f(βˆ’1)=2(βˆ’1)2βˆ’(βˆ’1)+1=2+1+1=4f(-1) = 2(-1)^2 - (-1) + 1 = 2 + 1 + 1 = 4

Therefore, f∘g∘f∘g∘f∘g(3)=4f \circ g \circ f \circ g \circ f \circ g (3) = 4.

b) Find the real values of xx for which f(g(x))≀2β‹…g(x)f(g(x)) \leq 2 \cdot g(x):

f(g(x))=2(xβˆ’2)2βˆ’(xβˆ’2)+1f(g(x)) = 2(x - 2)^2 - (x - 2) + 1 2(x2βˆ’4x+4)βˆ’x+2+12(x^2 - 4x + 4) - x + 2 + 1 =2x2βˆ’8x+8βˆ’x+2+1= 2x^2 - 8x + 8 - x + 2 + 1 =2x2βˆ’9x+11= 2x^2 - 9x + 11

Inequality:

2x2βˆ’9x+11≀2(xβˆ’2)2x^2 - 9x + 11 \leq 2(x - 2) 2x2βˆ’9x+11≀2xβˆ’42x^2 - 9x + 11 \leq 2x - 4 2x2βˆ’11x+15≀02x^2 - 11x + 15 \leq 0

Solve the quadratic inequality:

x=11Β±121βˆ’1204x = \frac{11 \pm \sqrt{121 - 120}}{4} x=11Β±14x = \frac{11 \pm 1}{4} x1=3andx2=52x_1 = 3 \quad \text{and} \quad x_2 = \frac{5}{2}

The values of xx that satisfy the inequality are 52≀x≀3\frac{5}{2} \leq x \leq 3.

Would you like more details or have any questions? Here are some additional problems you might consider:

  1. How do you solve quadratic equations by factoring?
  2. What is the process for finding the derivative of a function?
  3. How can you integrate a polynomial function?
  4. What are the properties of logarithms?
  5. How do you determine the convergence of a sequence?

Tip: Always verify your final answers by substituting them back into the original equations to ensure they satisfy all given conditions.

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Math Problem Analysis

Mathematical Concepts

Function composition
Quadratic equations
Function equality

Formulas

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Theorems

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Suitable Grade Level

Grades 11-12