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Zorluk: OrtaSolving Quadratic Equations by Factoring

What is the sum of all real values of xx that satisfy the equation (x3)2+x(x+2)=15(x - 3)^2 + x(x + 2) = 15?

  1. A
    -2
  2. B
    -1
  3. C
    0
  4. 2Cevap
  5. E
    4

Cevap

The sum of all real values of xx that satisfy the equation is 22.
Expanding the equation yields 2x24x+9=152x^2 - 4x + 9 = 15. Setting this to zero gives 2x24x6=02x^2 - 4x - 6 = 0. Dividing by the common factor of 22 simplifies this to x22x3=0x^2 - 2x - 3 = 0. Factoring the trinomial yields (x3)(x+1)=0(x - 3)(x + 1) = 0, which gives the two solutions x=3x = 3 and x=1x = -1. Summing these two solutions gives 3+(1)=23 + (-1) = 2.

Adım Adım Çözüm

1
Expand both terms on the left side of the equation.
(x26x+9)+(x2+2x)=15(x^2 - 6x + 9) + (x^2 + 2x) = 15
Applying the binomial squaring formula (ab)2=a22ab+b2(a - b)^2 = a^2 - 2ab + b^2 to (x3)2(x - 3)^2 and distributing xx to both terms in x(x+2)x(x + 2) allows us to simplify the equation.
2
Combine like terms and set the quadratic equation to zero.
2x24x6=02x^2 - 4x - 6 = 0
Grouping x2x^2 terms, xx terms, and constant terms on one side is necessary to format the quadratic equation as ax2+bx+c=0ax^2 + bx + c = 0 before factoring.
3
Divide the entire equation by the common factor of 22 to simplify factoring.
x22x3=0x^2 - 2x - 3 = 0
Simplifying the quadratic equation makes it easier to find two binomial factors.
4
Factor the quadratic trinomial by finding two numbers that multiply to 3-3 and add to 2-2.
(x3)(x+1)=0(x - 3)(x + 1) = 0
Since 3×1=3-3 \times 1 = -3 and 3+1=2-3 + 1 = -2, we can write the quadratic in factored form.
5
Set each factor to zero to solve for xx.
x=3x = 3 or x=1x = -1
Applying the zero product property determines the two values of xx that satisfy the original equation.
6
Calculate the sum of the two solutions.
3+(1)=23 + (-1) = 2
The question asks for the sum of all real values of xx that satisfy the equation.

Anahtar Kavram

Solving quadratic equations by rearranging terms, factoring trinomials, and applying the zero product property.
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