To determine which of the given quadratic equations can be solved by grouping, we typically check if we can find two numbers that multiply to the product of the coefficient of \(x^2\) (which is \(1\) in all these equations) and the constant term, while adding up to the coefficient of the linear term (\(x\)).
The general form of a quadratic equation is \(ax^2 + bx + c = 0\). In this case, \(a = 1\) for all equations.
1. \( x^2 + 8x - 22 = 0 \)
- Here, the product \(ac = 1 \cdot (-22) = -22\) and \(b = 8\).
- We need two numbers that multiply to \(-22\) and add to \(8\).
- The factors \(10\) and \(-2\) satisfy this condition: \(10 \cdot (-2) = -20\), not viable.
- This cannot be solved by grouping.
2. \( x^2 - 12x + 18 = 0 \)
- The product \(ac = 1 \cdot 18 = 18\) and \(b = -12\).
- We need factors that multiply to \(18\) and add to \(-12\).
- The numbers are \(-6\) and \(-6\) (since \(-6 + (-6) = -12\)); however, they don't fit grouping directly. Nevertheless, this format generally supports grouping.
3. \( x^2 - 4x - 8 = 0 \)
- The product \(ac = 1 \cdot (-8) = -8\) and \(b = -4\).
- We need to find two numbers that multiply to \(-8\) and add to \(-4\).
- The pairs (2 and -4) do not fit thusly.
4. \( x^2 + 10x + 21 = 0 \)
- The product \(ac = 1 \cdot 21 = 21\) and \(b = 10\).
- We need two numbers that multiply to \(21\) and add to \(10\).
- The numbers \(3\) and \(7\) do meet this condition: \(3 + 7 = 10\).
Now, summing this up, the second and fourth equations can potentially be solved by grouping, giving emphasis in this context particularly to \( x^2 - 12x + 18 = 0 \) and \( x^2 + 10x + 21 = 0 \).
Among these options, the quadratic equations that can truly be solved by grouping based on clear identifiable successful pair factorization are primarily \( x^2 - 12x + 18 = 0 \) and \( x^2 + 10x + 21 = 0 \).
In conclusion, the one more likely achievable cleanly through the grouping process is:
\( x^2 + 10x + 21 = 0 \).
Respectively, it has more fluid access through concepts of factoring by grouping.