Question

Tìm x

( x - 5 ) ( x + 5) - ( x + 3)^2 +3(x-2)^2 = ( x+1 )^2 - (x+4) (x-4) +3x^2

 

Answer 1

( x-5)(x+5)-(x+3)²+3(x-2)²=(x+1)²- (x+4)(x-4)+3x²

<=>(x²-25)-(x+3)²+3(x-2)²=(x+1)²+(16-x²)+3x²

<=>x²-25-x²-6x-9+3x²-12x+12=x²+2x+1+16-x²+3x²

<=>3x²-18x-22=3x²+2x+17

<=>-20x=39

=>x=-39/20