Question

como responder a questão y = x² -9 x + 18
y = -x²+ 12 x + 20

Answer 1

x² -9 x + 18

a=1

b=-9

c=18

∆=b²-4ac

∆=(-9)²-4*1*18

∆=81-72

∆=9

-b±√∆/2a

9±√9/2*1

9±3/2

x¹=9+3/2=12/2=>6

x²=9-3/2=6/2=>3

-x²+ 12 x + 20

x²-12x-20=0

a=1

b=-12

c=-20

∆=b²-4ac

∆=(-12)²-4*1*-20

∆=144+80

∆=224

-b±√∆/2a

12±√224/2*1

12±√224/2

12±√4²*14/2

12±√4²√14/2

12±4√14/2

x¹=12+4√14/2=6+2√14

x²=12-4√14/2=6-2√14