The question is about types and number of soultions so you must use b^2-4ac which is the experssion under the root in the quadratic formula so if b^2-4ac=0 then there is one real soultion if b^2-4ac<0 then there are two imaginary soultions that differ in the sign between them if b^2-4ac>0 then there are two real soultions so a polynomial is written in the form ax^2+bx+c=0 so a=-4 b=-4 c=-1 so b^2-4ac=16-16=0 so one real soultion is the answer you are looking type:real number:1
The mistake they made was they switched the slope and y-intercept.
The correct answer is y=2x+7 because when we write an equation in slope intercept form (y=mx+b) you replace m with the slope and b with the y-intercept.
