Question

Question 7 of 10

Describe the nature of the roots for this equation. x²+3x-7=0
A. One real, double root
B. Two real, irrational roots
C. Two real, rational roots
D. Two complex roots ​

Answer 1

B

Explanation:

Given a quadratic equation in standard form

ax² + bx + c = 0 ( a ≠ 0 )

Then the discriminant is

Δ = b² - 4ac

• If b² - 4ac > 0 then 2 real irrational roots

• If b² - 4ac > 0 and a perfect square then 2 real rational roots

• If b² - 4ac = 0 then 1 real double root

• If b² - 4ac < 0 then 2 complex roots

Given

x² + 3x - 7 = 0 ← in standard form

with a = 1, b = 3, c = - 7 , then

b² - 4ac

= 3² - (4 × 1 × - 7) = 9 + 28 = 37

Since b² - 4ac > 0 then 2 real irrational roots