Answer:
[tex]B=-5[/tex]
Step-by-step explanation:
we have
[tex]f(x)=3x^{2} -Bx+4[/tex]
we know that
f(-1) is the value of the function for x=-1
so
substitute the value of x=-1 in the function and solve for B
[tex]f(-1)=3(-1)^{2} -B(-1)+4[/tex]
we have
[tex]f(-1)=12[/tex]
substitute
[tex]12=3(-1)^{2} -B(-1)+4[/tex]
[tex]12=3-B+4[/tex]
[tex]12=7-B[/tex]
[tex]B=7-12[/tex]
[tex]B=-5[/tex]
