Question #85932

1 Answer
Mar 8, 2017

x=-1 and x=-4/5

Explanation:

5x^2+9x=-4

:.5x+9x+4=0

:.(x+1)(5x+4)

:.x+1=0 and 5x+4=0

:.color(blue)(x=-1 and 5x=-4

:.color(blue)(x=-1 and color(blue)(x=-4/5

substitute color(blue)(x=-1

:.5(color(blue)(-1))^2+9(color(blue)(-1))=-4

:.5(color(blue)(-1))(color(blue)(-1))-9=-4

:.5-9=-4

:.color(blue)(-4=-4

substitute color(blue)(x=-4/5

:.5color(blue)((-4/5))^2+9(color(blue)(-4/5))=-4

:.5(color(blue)(-4/5))(color(blue)(-4/5))+9(color(blue)(-4/5))=-4

:.5(16/25)-(36/5)=-4

:.80/25-36/5=-4/1

:.(80-180=-100)/25

:.color(blue)(-100=-100