398 algebra De mystif ieD
1
5050 450 400 1
50( xx^2 – + )( = 0 )x^2 − 9x + 8 = 0
(x − 8)(x − 1) = 0x
x– =
= 80
8x
x– =
= 10
1
If x = 1, the rent should be 400 + 25(1) = $425. If x = 8, the rent should
be 400 + 25(8) = $600.- P = 2.80 − 0.10x Q = 4000 + 200x
R = (2.80 − 0.10x)(4000 + 200x)
11,475 = (2.80 − 0.10x)(4000 + 200x)
11,475 = 11,200 + 160x − 20x^2
20 x^2 − 160x + 275 = 0
15 ( ^20 xx^2 – ^160 + ^275 ) = 51 ()^0
4 x^2 − 32x + 55 = 0
(2x − 5)(2x − 11) = 0
250
25
5
2
25
x
x
x
x
.– =
=
=
= 2110
211
11
2
55x
x
x
x
.– =
=
=
=
If x = 2.50, the price should be 2.80 − 0.10(2.5) = $2.55. If x = 5.5, the
price should be 2.80 − 0.10(5.50) = $2.25.- P = 4 − 0.05x Q = 500 + 20x R = (4 − 0.05x)(500 + 20x)
2450 = (4 − 0.05x)(500 + 20x)
2450 = 2000 + 55x − x^2
x^2 − 55x + 450 = 0
(x − 45)(x − 10) = 0
x
x– =
= 45 0
45x
x– =
= 10 0
10
If x = 45, the price should be 4 − 0.05(45) = $1.75 and 500 + 20(45) =
1400 buckets would be sold. If x = 10, the price should be 4 − 0.05(10) =
$3.50 and 500 + 20(10) = 700 buckets would be sold.