Question #2c02b

1 Answer
Nov 19, 2017

x_1=1 2/3~~1.667
x_2=1/5=0.2

Explanation:

ax^2+bx+c=0
x_(1,2)=(-b+-sqrt(b^2-4*a*c))/(2*a)


15x^2-28x+5=0
=>
a=15
b=-28
c=5
=>
x_(1,2)=(-(-28)+-sqrt((-28)^2-4*(15)*(5)))/(2*(15))=
=(28+-sqrt(784-300))/(30)=
=(28+-sqrt(484))/(30)=
=(28+-22)/(30)=
=>
x_1=(28+22)/(30)=50/30=5/3=1 2/3~~1.667
x_2=(28-22)/(30)=6/30=2/10=1/5=0.2