Question

-2xao quadrado +26x-84=0

Answer 1

-2x² + 26x - 84 = 0
-x² + 13x - 42 = 0
x² - 13x + 42 = 0 

bhaskara
b² -4ac
169 -4.1.42
169 - 168
delta = 1

-b +/- √Δ / 2a
13 +/- √1 / 2.1
13 +/- 1 / 2

x1 = 13+1/2 = 14/2 = 7
x2 = 13-1/2 = 12/2 = 6