A. Goal:
Find all real solutions ( x ) to the quadratic equation ( x^2 - 5x + 6 = 0 ).
B. Step-by-step solution:
Method 1: Factoring
Write the quadratic equation:
[ x^2 - 5x + 6 = 0 ]
Reason: Starting point, given equation.Find two numbers that multiply to ( c = 6 ) and add to ( b = -5 ):
Numbers are (-2) and (-3) because ((-2) \times (-3) = 6) and ((-2) + (-3) = -5).
Reason: Factoring trinomial into two binomials.Factor the quadratic:
[ (x - 2)(x - 3) = 0 ]
Reason: Express quadratic as product of two factors.Apply the zero product property:
Set each factor to zero:
[ x - 2 = 0 \quad \Rightarrow \quad x = 2 ]
[ x - 3 = 0 \quad \Rightarrow \quad x = 3 ]
Reason: If product is zero, one of the factors must be zero.
Method 2: Quadratic Formula
Write given coefficients:
[ a = 1, \quad b = -5, \quad c = 6 ]
Reason: Identify coefficients for formula.Write quadratic formula:
[ x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} ]
Reason: Formula solves any quadratic equation.Calculate discriminant:
[ \Delta = b^2 - 4ac = (-5)^2 - 4(1)(6) = 25 - 24 = 1 ]
Reason: Discriminant determines nature of roots.Apply formula:
[ x = \frac{-(-5) \pm \sqrt{1}}{2 \times 1} = \frac{5 \pm 1}{2} ]
Reason: Substitute values into formula.Calculate solutions:
[ x1 = \frac{5 + 1}{2} = 3, \quad x2 = \frac{5 - 1}{2} = 2 ]
Reason: Find exact roots of quadratic.
C. Verification:
Check both values in original equation ( x^2 - 5x + 6 = 0 ):
- For ( x = 2 ): [ 2^2 - 5(2) + 6 = 4 - 10 + 6 = 0 ]
- For ( x = 3 ): [ 3^2 - 5(3) + 6 = 9 - 15 + 6 = 0 ]
Both satisfy the equation.
D. Final answer:
[ \boxed{x = 2 \text{ or } x = 3} ]
E. Additional methods:
- Completing the square (not required here but a useful method).
- Graphical method (finding roots as ( x )-intercepts of ( y = x^2 - 5x + 6 )).
F. Key learning points:
- Always check signs carefully when factoring to avoid mistakes.
- Verify solutions by substituting back into the original equation.
G. Practice problems:
Solve ( x^2 - 7x + 10 = 0 )
Short answer: ( x = 2 ) or ( x = 5 )Solve ( x^2 + 2x - 8 = 0 )
Short answer: ( x = 2 ) or ( x = -4 )Solve ( 2x^2 - 3x - 2 = 0 )
Short answer: ( x = 2 ) or ( x = -\frac{1}{2} )
