The steps in writing f(x) = 18x + 3x2 in vertex form are shown, but a value is missing in the last step. write the function in standard form. f(x) = 3x2 + 18x factor a out of the first two terms. f(x) = 3(x2 + 6x) form a perfect square trinomial. f(x) = 3(x2 + 6x + 9) – 3(9) write the trinomial as a binomial squared. f(x) = 3(x + – 27 what is the missing value in the last step?

the answer is b

answer: c, the green line

step-by-step explanation:

there is no black line, eliminate b.

simple interest implies periodic payments, but the red line shows no payments, eliminate d.

simple interest has equal payments. if paid say every day, the graph is about a straight line (actually a stairstep).

the yellow line is not straight, eliminate a.

check: the green line is straight, answer is c.

simple interest with positive interest rate gives a straight line sloping up to the right. green line:

g(t) = $100 + ($200-$100) ÷ (20 years) × (t years)

= $100 + (4%/year) × ($100)(t years)

incidentally, the yellow line curving upward represents continuously compounded interest

y = $100 × 2^(t years / (14 assuming the yellow line hits $200 at 14 years. 2^0 is 1, so y(0) = $100; 2^(14/14) is 2, so y(14) = $200.