Respuesta :
Answer:
A.x=3
B.x=-7
Step-by-step explanation:
Hi, to answer this question we have to apply the quadratic formula:
For: ax2+ bx + c
x =[ -b ± √b²-4ac] /2a
Replacing with the values given:
x =[ -4 ± √(4)²-4(1)-21] /2(1)
x = [-4 ± √16 +84] /2
x = [ -4 ± √100] /2
x = [ -4 ± 10] /2
Positive:
x = [-4 + 10] /2 = 6 /2 = 3
Negative:
x = [ -4 - 10] /2 = -14/2 = -7
So, the solutions are :
A.x=3
B.x=-7
Feel free to ask for more if needed or if you did not understand something.
