Question

Find the nature of the roots of 4x ^ 2 + 6x - 7 = 0

a. complex
b. irrational
c. rational
d. real and equal

Answer 1

b

Explanation:

given a quadratic equation in standard form

ax² + bx + c = 0 (a ≠ 0 )

the discriminant b² - 4ac informs us about the nature of the roots

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

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

• If b² - 4ac = 0 then roots are real and equal

• If b² - 4ac < 0 the roots are complex

4x² + 6x - 7 = 0 ← is in standard form

with a = 4, b = 6, c = - 7 , then

b² - 4ac = 6² - (4 × 4 × - 7) = 36 - (- 112) = 36 + 112 = 148

since b² - 4ac > 0 then roots are real and irrational