Question

Tìm x : 

A) 3 ( 6x - 5 )( 4x + 1 ) - ( 8x + 3 )( 9x - 2 ) = 203

Answer 1

a, 3(6x−5)(4x+1)−(8x+3)(9x−2)=2033(6x−5)(4x+1)−(8x+3)(9x−2)=203

⇒3(24x2+6x−20x−5)−(72x2−16x+27x−6)=203⇒3(24x2+6x−20x−5)−(72x2−16x+27x−6)=203

⇒72x2−42x−15−72x2−11x+6=203⇒72x2−42x−15−72x2−11x+6=203

⇒−53x=203−6+15=212⇒−53x=203−6+15=212

Answer 2

nhầm òi 

 3(6x−5)(4x+1)−(8x+3)(9x−2)=2033(6x−5)(4x+1)−(8x+3)(9x−2)=203

⇒3(24x2+6x−20x−5)−(72x2−16x+27x−6)=203⇒3(24x2+6x−20x−5)−(72x2−16x+27x−6)=203

⇒72x2−42x−15−72x2−11x+6=203⇒72x2−42x−15−72x2−11x+6=203

⇒−53x=203−6+15=212⇒−53x=203−6+15=212

⇒x=−4

Answer 3

3\left(6x-5\right)\left(4x+1\right)-\left(8x+3\right)\left(9x-2\right)=2033(6x−5)(4x+1)−(8x+3)(9x−2)=203

\Leftrightarrow\left(18x-15\right)\left(4x+1\right)-\left(72x^2+27x-16x-6\right)=203⇔(18x−15)(4x+1)−(72x2+27x−16x−6)=203

\Leftrightarrow72x^2-60x+18x-15-72x^2-27x+16x+6=203⇔72x2−60x+18x−15−72x2−27x+16x+6=203

\Leftrightarrow\left(72x^2-72x^2\right)+\left(18x+16x-60x-27x\right)-\left(15-6\right)=203⇔(72x2−72x2)+(18x+16x−60x−27x)−(15−6)=203

\Leftrightarrow-53x-9=203⇔−53x−9=203

\Leftrightarrow-53x=212⇔−53x=212

\Leftrightarrow x=-4⇔x=−4

Vậy x=-4x=−4