A ten-foot-long board is cut into three pieces. The second piece is half as long as the first. The third piece is 4 feet longer than the second. How long is the first piece?

Answer: 2 3/4 feet

If f(x)=2x2+1/2x-4, what is f(-1/2)?

Answer: -15/4

**I am studying for a test and am trying to figure out how to solve for these problems**. I have the answers but I don't know how to get to it. Please help me understand, thanks.

1 answer

pieces:
x
x/2
x/2+4

x + x/2 + x/2+4 = 10
2x = 6
x = 3

check: 3 + 1.5 + 5.5 = 10

How did they come up with 2 3/4?
I suspect a typo.

f(-1/2) = 2(1/4) - 1/4 - 4 = -15/4