x² + 7x/10 = 1/7
x² + 7x/10 - 1/7 = 0
Δ = b² - 4.a.c
Δ = (7/10)² - 4 . 1 . (-1/7)
Δ = 0,48999999999999994 - 4. 1 . (-1/7)
Δ = 1,0614285714285714
Há 2 raízes reais.
x = (-b +- √Δ)/2a
x' = (-(7/10) + √1,0614285714285714)/2.1
x'' = (-(7/10) - √1,0614285714285714)/2.1
x' = 0,3302565561201596 / 2
x'' = -1,7302565561201595 / 2
x' = 0,1651282780600798
x'' = -0,8651282780600797
Rounding
x' = 0,17
x'' = -0,87