Question

If $x = 3 - \sqrt{2}$ then find the value of $3x^2+ 2x - 4$

• A. $$20-\sqrt{2}$$
• B. $$35+\sqrt{2}$$
• C. $$35-20\sqrt{2}$$
• D. $$35-2\sqrt{2}$$

Answer 1

Answer:

$$35-20\sqrt{2}$$

$3x ^ 2 + 2x - 4$

$= 3 \times (3 - \sqrt{2}) ^ 2 + 2(3 - \sqrt{2}) - 4$

$= 3(11 - 6\sqrt{2}) + 6 - 2\sqrt{2} - 4$

$= 35 - 20\sqrt{2}$