Quadratic relations

Question

Given y=x^2-4x-21 find each of the following 

y-intercept 

x-intercept 

coordinates of vertex 

is the parabola max or min value 

the max or min value 

 

Answer 1

                                                         This is  A COMPUTER GENERATED SOLUTION

x2−4x−21=0
The solutions are:

x1=7x2=−3
Explanation

STEP1: Find coefficients a , b and c

x1,2=−b±b2−4ac−−−−−−−√2a
x1,2=−(−4)±(−4)2−4⋅1⋅(−21)−−−−−−−−−−−−−−−−√2⋅1
STEP3: Simplify expression under the square root.

x1,2=4±100−−−√2
STEP4: Solve for x

x1=4 + 100−−−√2=7
x2=4 − 100−−−√2=−3