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(x+1)²-5x²=2(x-3)²-(x+2)²

Răspuns :

x²+2x+1-5x²=2(x²-6x-9)-x²+4x+4
x²+2x+1-5x²=2x²-12x-18-x²+4x+4
x²+2x+1-5x²=x²-8x-14
x²-x²+10x-5x²=-1-14
-5x²+10x=-15
x(-5x+10)=-15

-5x+10=-15
-5x=-15-10
-5x=-25
x=5
Clau2ask
(x+1)²-5x²=2(x-3)²-(x+2)² ⇔
x²+2x+1-5x² = 2( x² - 6x +9) -x²-4x-4
-4x²+2x+1= 2x² -12x+18-x²-4x-4
-5x²+18x-13=0
Δ=b²-4ac= 18²-4*(-5)*(-13)= 324-260 = 64                √Δ=√64=8
x₁= -b+√Δ/2a=-18+8/2*(-5) = -10/-10=1
x₂= -b- √Δ/2a = -18 -8 / 2*(-5) = -26/ -10 =2.6