pt⇔(4x+5)2(4x+6)(4x+4)=72⇔(16x2+40x+25)(16x2+40x+24)=72" role="presentation" style="font-family: "Open Sans", sans-serif; display: inline; line-height: normal; font-size: 14.6667px; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;">(4x+5)2(4x+6)(4x+4)=72⇔(16x2+40x+25)(16x2+40x+24)=72pt⇔(4x+5)2(4x+6)(4x+4)=72⇔(16x2+40x+25)(16x2+40x+24)=72
Đặt 16x2+40x+24=a" role="presentation" style="font-family: "Open Sans", sans-serif; display: inline; line-height: normal; font-size: 14.6667px; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;">16x2+40x+24=a16x2+40x+24=a
Ta có: a(a+1)=72⇔a2+a−72=0⇔(a−8)(a+9=0⇔...)" role="presentation" style="font-family: "Open Sans", sans-serif; display: inline; line-height: normal; font-size: 14.6667px; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;">a(a+1)=72⇔a2+a−72=0⇔(a−8)(a+9=0⇔...)