Tìm x, y, biết: a) x^2 +4x = 0 b) 5x (3x -2) = 4 -9x^2
Giải thích
a)
x2+4x=0xx+4=0⇒x=0x+4=0⇒x=0x=−4
Vậy x∈−4; 0
b)
5x3x−2=4−9x25x3x−2=2−3x2+3x5x3x−2−2−3x2+3x=05x3x−2+3x−22+3x=03x−25x+2+5x=03x−28x+2=0⇒3x−2=08x+2=0⇒x=23x=−14
Vậy x∈−14; 23
a)
x2+4x=0xx+4=0⇒x=0x+4=0⇒x=0x=−4
Vậy x∈−4; 0
b)
5x3x−2=4−9x25x3x−2=2−3x2+3x5x3x−2−2−3x2+3x=05x3x−2+3x−22+3x=03x−25x+2+5x=03x−28x+2=0⇒3x−2=08x+2=0⇒x=23x=−14
Vậy x∈−14; 23