C©u 3: T×m x biết
(-x – 6) (x + 9) = 0
-2.(x + 3) – 15 = 3. (4 + 2x) + 7
C©u 3: T×m x biết (-x – 6) (x + 9) = 0 -2.(x + 3) – 15 = 3. (4 + 2x) + 7
By Isabelle
By Isabelle
C©u 3: T×m x biết
(-x – 6) (x + 9) = 0
-2.(x + 3) – 15 = 3. (4 + 2x) + 7
(-x – 6) (x + 9) = 0
=>-x-6=0 hoặc x+9=0
=>x=-6 hoặc x=-9
Vậy…
-2.(x + 3) – 15 = 3. (4 + 2x) + 7
=>-2x-6-15=12+6x+7
=>-2x-6x=12+7+6+15
=>-8x=40
=>x=-5
Vậy x=-5
(-x-6).(x+9)=0
<=> -x-6=0 hoặc x+9=0
<=> x=-6 hoặc x=-9
-2.(x+3)-15=3.(4+2x)+7
<=> -2x-6-15= 12+6x+7
<=> 8x=-40 <=> x=-5