54 because if x+y=82 and x-y=26 add 26 and 82 is 108 the divide it by 2 your answer is 54
I would say that the "n"th term of the sequence is 41, as the pattern increases by 10 every term.
Carry out the mult.: f(x) = -[x^2 - 21x + 9x - 189]
Combine like terms: f(x) = -[x^2 - 12x - 189]
Eliminate the brackets [ ]: f(x) = -x^2 + 12x + 189
Identify coefficients a, b and c: a= -1, b=12, c=189
The equation of the axis of symmetry is x = -b/(2a), which here equals
x = -(12)/[2(-1)], or x = 6
This is also the x-coordinate of the vertex. Plug x=6 into the original equation to calculate the y-coordinate.
An expression to represent a decimal between 1 and 10 multiplied by ten. basically to write larger numbers with less digits.
ex . 100 = 1 x 10^2
ex. 4321= 4.321 x 10^3