Justify means plug answer in and verify
so distribute 8(3-7x)=24-56x
143=7+24-56x
143=31-56x
minus 31 both sides
112=-56x
divide both sides by -56
-2=x
justify
plug it back
143=7+8(3-7x)
143=7+8(3-7(-2))
143=7+8(3-(-14))
143=7+8(3+14)
143=7+8(17)
143=7+136
143=143
true
x=-2
Here go to this website, it will explain everything
https://www.symbolab.com/solver/quadratic-equation-calculator/2x%5E%7B2%7D-4x+5=0
√214= 14.6287388383278
Calculator maybe??
I assume you're asking where it meets the y axis
In an equation the last number is the y intercept so I'm this case it would be 1