What is 7% tax on a $9.79 purchase
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Answer:
n = 6 + or n = 6 -
Step-by-step explanation:
We can solve this equation using the quadratic formula OR Completing the Square method.
n² + 14 = 12n
rearrange : n² - 12n + 14 = 0
here a= 1 , b = -12, c = 14
the quadratic formula says: x = - b/ (2a) + root(b^2 - 4ac) / (2a)
or x = - b/ (2a) - root(b^2 - 4ac) / (2a)
x = - (-12)/ (2) + root((-12)^2 - 4*14) / (2)
x = 6 + root (144 - 56) / 2
x = 6 + root(88)/2
x = 6 + root(4*22) / 2
x = 6 + 2*root(22)/2
x = 6 + root(22) = 6 +
so x =6 + or x = 6 -
In this case x = n
n = 6 + or n = 6 -