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(x+3)(4x-5)=(2x-3)(2x+3)
x=?
multumesc


Răspuns :

4x^2-5x+12x-15=4x^2-9 | (-4x^2) ......... -5x+12x-15=-9 7x=6 x=6/7
( x + 3 ) ( 4x - 5 ) = ( 2x - 3 ) ( 2x + 3 )
4x² - 5x + 12x - 15 = 4x² + 6x - 6x - 9
4x² + 7x - 15 = 4x² - 9 ( 4x² cu 4x² se taie )
7x = - 9 + 15
7x = 6
x = 6/7