Math Problem Statement

Quiz 3.pdf

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solve each question

Solution

Let's break down and solve each of the questions from the quiz:

1. Solve the following equations by factorization:

a. x2x=12x^2 - x = 12

We rearrange the equation as: x2x12=0x^2 - x - 12 = 0 Factorizing this quadratic equation: (x4)(x+3)=0(x - 4)(x + 3) = 0 Thus, the solutions are: x=4orx=3x = 4 \quad \text{or} \quad x = -3

b. x2+30=xx^2 + 30 = x

Rearrange the equation: x2x+30=0x^2 - x + 30 = 0 The discriminant Δ=(1)24(1)(30)=1120=119\Delta = (-1)^2 - 4(1)(30) = 1 - 120 = -119, so there are no real solutions, only complex ones.

c. 2x2+6x=162x^2 + 6x = -16

Rearrange the equation: 2x2+6x+16=02x^2 + 6x + 16 = 0 Dividing by 2: x2+3x+8=0x^2 + 3x + 8 = 0 The discriminant is Δ=324(1)(8)=932=23\Delta = 3^2 - 4(1)(8) = 9 - 32 = -23, so there are no real solutions, only complex ones.

d. 4x217=x4x^2 - 17 = x

Rearrange the equation: 4x2x17=04x^2 - x - 17 = 0 Using the quadratic formula: x=(1)±(1)24(4)(17)2(4)x = \frac{-(-1) \pm \sqrt{(-1)^2 - 4(4)(-17)}}{2(4)} x=1±1+2728=1±2738x = \frac{1 \pm \sqrt{1 + 272}}{8} = \frac{1 \pm \sqrt{273}}{8} So, the solutions are: x=1+2738orx=12738x = \frac{1 + \sqrt{273}}{8} \quad \text{or} \quad x = \frac{1 - \sqrt{273}}{8}

2. Find the x-intercept (abscisse à l’origine) of the following equations:

a. 2x2+3x40=02x^2 + 3x - 40 = 0

Using the quadratic formula: x=3±324(2)(40)2(2)x = \frac{-3 \pm \sqrt{3^2 - 4(2)(-40)}}{2(2)} x=3±9+3204=3±3294x = \frac{-3 \pm \sqrt{9 + 320}}{4} = \frac{-3 \pm \sqrt{329}}{4} The solutions are: x=3+3294orx=33294x = \frac{-3 + \sqrt{329}}{4} \quad \text{or} \quad x = \frac{-3 - \sqrt{329}}{4}

b. 4x2+8x12=04x^2 + 8x - 12 = 0

Dividing by 4: x2+2x3=0x^2 + 2x - 3 = 0 Factorizing: (x1)(x+3)=0(x - 1)(x + 3) = 0 The solutions are: x=1orx=3x = 1 \quad \text{or} \quad x = -3

c. x26x16=0x^2 - 6x - 16 = 0

Using the quadratic formula: x=(6)±(6)24(1)(16)2(1)x = \frac{-(-6) \pm \sqrt{(-6)^2 - 4(1)(-16)}}{2(1)} [ x = \frac{6 \

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Equations
Factorization
Quadratic Formula
Discriminants

Formulas

Quadratic equation formula: ax^2 + bx + c = 0
Factorization of quadratic expressions: (x - p)(x - q) = 0
Quadratic formula: x = (-b ± √(b^2 - 4ac)) / 2a

Theorems

Quadratic formula
Properties of discriminants
Factorization methods

Suitable Grade Level

Grades 8-10