Answer:
A. 5x² - 7 - 72 = 0
5x² - 79 = 0
x = ± √-4ac / 2a
x = ± √- 4 (5) (-79) / 2 (5)
x = ± √ 1580 / 10
x = ± 39.749/10
x = + 39.749/10 x = -39.749/10
= 3.9749 = - 3.9749
B. x² + 2x - 5 = 0
x = - b ± √b² - 4ac / 2a
= - 2 ± √2² - 4 (1) (-5) / 2 (1)
= - 2 ± √4 + 20 / 2
= - 2 ± √ 24 / 2
x = - 2 + 4.898 /2 x = - 2 - 4.898 / 2
= 2.898/2 = -6.898/2
= 1.449 = - 3.449
C. 3x² + 2x - 4 = 0
x = - b ± √b² - 4ac / 2a
= - 2 ± √2² - 4 (3) (-4) / 2 (3)
= - 2 ± √4 + 48 / 6
= - 2 ± √ 52 / 6
x = - 2 + 7.211 /6 x = - 2 - 7.211 / 6
= 5.211/6 = - 9.211 /6
= 0.869 = - 1.535
Hope that helps
Please to re-check answers
