SVP aidez moi a résoudre ces equations a) (2x-3)+(5x+9)=0 b) (2x-3)(5x+9)=-27 c) 4x2 +12x+9=0 d) 49x2 -25=0 e) 2x-36=5x+9-7 f) x2 =24

Réponse:

a) (2x-3)+(5x+9)=0

2x-3+5x+9=0

7x+6=0

7x=-6

x = -6/7

b) (2x-3)(5x+9)=-27

10x²+18x-15x-27=-27

10x²+3x=0

x(10x+3)=0

10x+3=0 ou x=0

10x=-3

x = -3/10

S ={-3/10; 0}

c) 4x² +12x+9=0

(2x+3)² =0

2x+3=0

2x = -3

x = -3/2

d) 49x² -25=0

(7x)²-5² =0

(7x-5)(7x+5)=0

7x-5 = 0 ou 7x+5=0

7x=5 ou 7x=-5

x = 5/7 ou x = -5/7

S ={-5/7; 5/7}

e) 2x-36=5x+9-7

2x-36 = 5x+2

2x-5x=2+36

-3x = 38

x = -38/3

f) x² =24

x = -√24 ou x = √24

x = -2√6 ou x = 2√6