Question

resolva a equaçao X² - 3X = 28

Answer 1

$\\ x^2 - 3x = 28 \\ x^2 - 3x - 28 = 0 \\ \Delta = b^2 - 4ac \\ \Delta = 9 + 112 \\ \Delta = 121 \\\\ x = \frac{- b \pm \sqrt{\Delta }}{2a} \Rightarrow x = \frac{3 \pm \sqrt{121}}{2} \Rightarrow x = \frac{3 \pm 11}{2} \\\\ \begin{cases} x' = \frac{3 + 11}{2} \rightarrow \boxed{x' = 7} \\ x'' = \frac{3 - 11}{2} \rightarrow \boxed{x'' = - 4}\end{cases}$

Answer 2

x²-3x-28=0

Δ= b²-4ac

Δ=(-3)²-4.1.(-28)

Δ= 9+112

Δ= 121

 

X= -b+-√Δ

         2.a

X= -(-3)+-√121

             2.2              

X= 3+-11

         4

X'=3+11/4=7

X"=3-11/4=-4