Question

alguém pode resolve-la pra mim? (-x+1)²=81

Answer 1

-x . -x + 1 = 81
x+1=81
x= 81-1
x= 80

Answer 2

(-x+1) (-x+1)= x²-x-x+1= x²-2x+1 = 81
x²-2x-80=0
b²-4ac
(-2)² - 4(1)(-80)
4+320
Δ= 324
-b +- √Δ / 2a
-(-2) +- 18/ 2=  2+-18/2
X₁= 10
X₂= -7