Respuesta :
Answer:
y = x² + 7x + 4
Step-by-step explanation:
First option
System of equations:
y = x² + x – 4
y = x – 5
Replacing:
x - 5 = x² + x – 4
0 = x² + x – 4 - x + 5
0 = x² + 1
Discriminant:
b²-4*a*c
0²-4*1*1
-4 < 0 then the equation has no real roots
Second option
System of equations:
y = x² + 2x – 1
y = x – 5
Replacing:
x - 5 = x² + 2x – 1
0 = x² + 2x - 1 - x + 5
0 = x² + x + 4
Discriminant:
b²-4*a*c
1²-4*1*4
-15 < 0 then the equation has no real roots
Third option
System of equations:
y = x² + 6x + 9
y = x – 5
Replacing:
x - 5 = x² + 6x + 9
0 = x² + 6x + 9 - x + 5
0 = x² + 5x + 4
Discriminant:
b²-4*a*c
5²-4*1*4
9 > 0 then the equation has two different real roots
Fourth option
System of equations:
y = x² + 7x + 4
y = x – 5
Replacing:
x - 5 = x² + 7x + 4
0 = x² + 7x + 4 - x + 5
0 = x² + 6x + 9
Discriminant:
b²-4*a*c
6²-4*1*9
0 then the equation has one real root
