Answer:
x = 2 ± (i)√5 (Answer b)
Step-by-step explanation:
x²-4x+9=0 can be solved in a variety of ways; the first two that come to mind that are also appropriate are (1) completing the square and (2) using the quadratic formula.
Completing the square is fast here:
Rewrite x²-4x+9=0 as x²-4x +9=0
Identify the coefficient of the x term: it is -4
Take half of that, obtaining -2
Square this result, obtaining 4
Add 4 to x²-4x +9=0, in the blank space in the middle, and then subtract 4: x²-4x +4 -4 +9=0
Rewrite x²-4x +4 as the square of a binomial:
(x - 2)² - 4 + 9 = 0 → (x - 2)² = -5
Take the square root of both sides: x - 2 = ±√(-5) = ± (i)√5
Then x = 2 ± (i)√5
Answer:
$4.80
Step-by-step explanation:
6 oranges for 1.80
sp 6 divided by 1.80 comes out to 0.3 per orange
0.3 times 16 comes out to 4.80
therefor $4.80
We have three numbers to arrange so that 6 is 1/10 of the value of the other six.
Since position tells us whether we're talking about single, tens, hundreds, thousands (e.g. 25 is two times 10 plus five times 1) we know that the two sixes must be next to each other.
This leaves us with two options.
663 or 366.
In each of these cases the second 6 in the number is one tenth of the first 6.
If we look at the only other option: 636 we see that the second 6 is one hundredth of the value of the first 6.
P=98 m
l +9=4w
p=2l+2w
98=2(4w-9) +2w
98 = 8w-18+2w
116=10w
w=11,6 m
l = 4w-9 = 4*11,6 -9 = 46,4 -9 = 37,4 m
w=11,6 m
l= 37,4 m
