Answer
x=4 3/5
Step-by-step explanation:
Add 1/5 to both sides, getting rid of the -1/5 on the left and adding 1/5 to 4 2/5
4 2/5
+1/5
----------
4 3/5
Everyone should do this derivation, because otherwise the "quadratic formula" is some sort of "magic" LOL...
ax^2+bx+c=0
x^2+bx/a+c/a=0
x^2+bx/a=-c/a
x^2+bx/a+b^2x/(4a^2)=b^2/(4a^2)-c/a
(x+b/(2a))^2=(b^2-4ac)/(4a^2)
x+b/(2a)=±√(b^2-4ac)/(2a)
x=-b/(2a)±√(b^2-4ac)/(2a)
x=(-b±√b^2-4ac)/(2a)
Answer:
number 4 is 87 vertical angles are congruent