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PLS HELP.... If 4x^2 + bx + 9 = 0, where b is the constant, has exactly one solution, what is a possible value of b ?
A. 72
B. 36
C. 12
D. 6

Respuesta :

you can use the discriminant rule, which is :
b^2 -4ac
“exactly one solution” means that it is equal to zero
so:
b^2 -4(4)(9)=0
b^2 -4(36)=0
b^2 -144=0
b^2=144
square root both sides
b=12 or -12

hope this helps !

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