(3x+a)(4x+a)=12x^2+28x+b

The equation above is true for all values of x, and a and b are constants. What is the value of b ?

A)
B)
C)
D)

 


 

Comments (1)

take the oi out of the Foil
F=3x*4x
O and I is
a(4x) +a( 3x)= 28x
L is a^2

a( 3+4)=28 remove the x because we are just intertested in the number
a(7) = 28 or (4*3) + (4*4)
a=4
L = a^2 or 16 b= a^2 or 16

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