Jawabanmu

2013-12-10T19:04:10+07:00
3x(-x+5) = -3x+15x
2x(5x+3) = 10x+6x
(x+4)(x+5) = x(x + 5) +4(x + 5) = x + 5x + 4x + 20 = 10x + 20
2013-12-10T19:42:21+07:00
3x(-x+5) = 3  x^{2} +15x

2x(5x+3) = 10 x^{2} +6x

(x+4)(x+5) = x(x+5)+4(x+5) =>  x^{2} +5x+4x+20 =>  x^{2} +9x+20