B
given a quadratic equation in standard form
ax² + bx + c = 0
Then we can describe the nature of the roots using the discriminant
Δ = b² - 4ac
• if b² - 4ac > 0, then 2 real, distinct and irrational roots
• if b² - 4ac > 0 and a perfect square, then real and rational roots
• if b² - 4ac = 0, then real and equal roots
• if b² - 4ac < 0, then roots are not real
for x² + 9x + 14 = 0
with a = 1, b= 9 and c = 14, then
b² - 4ac = 9² - (4 × 1 × 14 ) = 81 - 56 = 25
Since b² - 4ac > 0 and a perfect square, then roots are real and rational
