Question

Nilai r yang memenuhi -8 = -2r[r + 3]adalah..

Answer 1

-2r(r+3)= -8
-2r²+6r= -8
-2r²+6r+8 = 0
( -2r+ 8 )( r+ 1 ) = 0
a.
2r = -8 
r = -8/2
r = -4

b.
r= -1

Jawabannya r1 = -8 ; r2 = -1