Math Problem Statement

Solve the quadratic equations: 1. x^2 + 14x + 49 = 4 and 2. x^2 - 6x + 9 = 20.

Solution

Let's solve the equations step by step.

1. x2+14x+49=4x^2 + 14x + 49 = 4

  1. Subtract 44 from both sides to set the equation equal to zero: x2+14x+494=0x^2 + 14x + 49 - 4 = 0 x2+14x+45=0x^2 + 14x + 45 = 0

  2. Factor the quadratic: x2+14x+45=(x+9)(x+5)x^2 + 14x + 45 = (x + 9)(x + 5)

  3. Solve for xx by setting each factor to zero: x+9=0orx+5=0x + 9 = 0 \quad \text{or} \quad x + 5 = 0 x=9orx=5x = -9 \quad \text{or} \quad x = -5

Solution for 1:

x=9orx=5x = -9 \quad \text{or} \quad x = -5


2. x26x+9=20x^2 - 6x + 9 = 20

  1. Subtract 2020 from both sides: x26x+920=0x^2 - 6x + 9 - 20 = 0 x26x11=0x^2 - 6x - 11 = 0

  2. Factor or use the quadratic formula. This does not factor neatly, so use the quadratic formula: x=b±b24ac2ax = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} Here, a=1a = 1, b=6b = -6, c=11c = -11.

    Substitute into the formula: x=(6)±(6)24(1)(11)2(1)x = \frac{-(-6) \pm \sqrt{(-6)^2 - 4(1)(-11)}}{2(1)} x=6±36+442x = \frac{6 \pm \sqrt{36 + 44}}{2} x=6±802x = \frac{6 \pm \sqrt{80}}{2} Simplify 80\sqrt{80}: 80=45\sqrt{80} = 4\sqrt{5} So: x=6±452x = \frac{6 \pm 4\sqrt{5}}{2} Simplify further: x=3±25x = 3 \pm 2\sqrt{5}

Solution for 2:

x=3+25orx=325x = 3 + 2\sqrt{5} \quad \text{or} \quad x = 3 - 2\sqrt{5}


Would you like further details or help with a specific step? Here are related questions for practice:

  1. How do you determine if a quadratic is factorable?
  2. What is the discriminant, and how does it help in solving quadratics?
  3. Can you convert x=3±25x = 3 \pm 2\sqrt{5} into a decimal approximation?
  4. What are perfect square trinomials, and how do you recognize them?
  5. Can you rewrite the quadratic formula derivation step by step?

Tip: Always check if a quadratic can be factored easily before using the quadratic formula! It saves time and simplifies the process.

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Equations
Factoring
Square Root Property

Formulas

Factoring: (x + a)(x + b) = 0
Quadratic Formula: x = [-b ± √(b^2 - 4ac)] / 2a

Theorems

Quadratic Formula
Properties of Perfect Squares

Suitable Grade Level

Grades 8-10