Problem

The equation $x^{2}-8 x+5=0$ can be solved using more than one method. What characteristic of the equation indicates that each method below is or is not a valid technique to use?
Since the middle term is an even number, taking half and squaring would give a whole number, which makes
[ Select ]
[ Select ] method to use.
Since the expression is not factorable, the
[Select] is
[ Select ] method to use.
This equation is trinomial so [ Select ]
[ Select ] a good method to use.
This trinomial does not factor so
[ Select ] is not an option.

Answer

Expert–verified
Hide Steps
Answer

Then \(a = \frac{1}{2}\), so the roots are \(\boxed{-2,\frac{3}{2}}\).

Steps

Step 1 :Let the quadratic be \(x^2 + ax + b\). Then the roots are \(a + 1\) and \(b + 1\). By Vieta's formulas,

Step 2 :\begin{align*} (a + 1) + (b + 1) &= -a, \\ (a + 1)(b + 1) &= b. \end{align*}

Step 3 :From the first equation, \(a + 1 = -\frac{b}{2}\). Substituting into the second equation, we get

Step 4 :\[-\frac{b}{2} (b + 1) = b.\]

Step 5 :Since \(b\) is non-zero, we can divide both sides by \(b\), to get \(-\frac{1}{2} (b + 1) = 1\). This leads to \(b = -3\).

Step 6 :Then \(a = \frac{1}{2}\), so the roots are \(\boxed{-2,\frac{3}{2}}\).

link_gpt