Réponse :
bonjour
Explications étape par étape
1)
5x + 7 = 2x - 9 =
3x + 16=0
3x + (16)=0
x= − (16)3
x=−163
2) (2x-10)(5x+14)=0
10x2−22x−140=0
(10)⋅x2+(−22)⋅x+(−140)=0
x=−(−22)±(−22)2−4⋅(10)⋅(−140)−−−−−−−−−−−−−−−−−−−−−−√2⋅(10)
x=22±484−(−5600)−−−−−−−−−−−−−√20
x=22±6084−−−−√20
x=22±(78)20
x1=10020=(20)⋅(5)(20)=5
x2=−5620=(4)⋅(−14)(4)⋅(5)=−145
