Answer:
10. x = 3 ± 2√6
11. x = 4 ± √6
12.
and 
Step-by-step explanation:
10. Given the quadratic equation (x - 3)² + 14 = 38
We have to solve it by square root.
Now, (x - 3)² + 14 = 38
⇒ (x - 3)² = 38 - 14 = 24
⇒ (x - 3)² = (2√6)²
Now, square rooting both sides we get,
(x - 3) = ± 2√6
⇒ x = 3 ± 2√6 (Answer)
11. Given the quadratic equation x² - 8x + 10 = 0
We have to solve it by completing the square.
Now, x² - 8x + 10 = 0
⇒ x² - 2(4)(x) + 4² = 4² - 10
⇒ (x - 4)² = (√6)²
Now, square rooting both sides we get,
x - 4 = ± √6
⇒ x = 4 ± √6 (Answer)
12. Given the quadratic equation 5x² + 7x - 3 = 0
We have to solve it by quadratic formula.
Hence,
and 
⇒
and
(Answer)