Réponse :
Bonjour
Explications étape par étape :
a.
[tex]2x^{2} -5x = 0\\x (2x -5) = 0\\x = 0\\2x -5 = 0\\2x = 5\\x = 5/2[/tex]
b.
[tex](x+2)^{2} - (x+2)(6x -1) = 0\\(x+2)(x+2) - (x+2)(6x-1) = 0 \\(x+2)(x+2-(6x-1))=0\\(x+2)(-5x +3) = 0\\x +2 = 0 \\x = -2\\\\-5x +3 = 0\\-5x = -3 \\x = -3/-5 = 3/5[/tex]
c.
[tex](x-4)(x+1) = (x-4)(2x-5)\\x^{2}+x-4x-4 = 2x^{2} -5x-8x +20\\x^{2} -3x -4 = 2x^{2} -13x +20\\x^{2} -3x-4-2x^{2} +13x-20 = 0\\-x^{2} +10x -24 = 0\\x^{2} -10x +24 = 0\\x^{2} -4x -6x +24 = 0\\x(x-4)-6(x-4) = 0\\(x-4)(x-6) = 0\\x-4 = 0\\x = 4\\\\x-6 = 0\\x = 6[/tex]
d.
[tex](x-2)^{2} =49\\x-2 = -7\\x-2 = 7\\\\x-2 = -7\\x = -7+2\\x = -5\\\\x-2 = 7\\x = 7+2\\x = 9[/tex]
