Question

x is the lowest value for which x(x(125x+300)+240)+64 is equal to 0. Calculate
the value of 5 times x.

Answer 1

x(x(125x+300)+240)+64=0;

125x^3+300x^2+240x+64=0;

(5x+4)(5x+4)(5x+4)=0;

5x+4=0 or 5x+4=0 or 5x+4=0;

x1=x2=x3= -0.8;

5x=5(-0.8)=-4

Answer: -4.