Answer:
3
Step-by-step explanation:
The answer is 3 because 3 pounds would equal $23.31.
$46.69 (what she had left) plus $23.31 (the 3 pounds she bought) = $70.
Answer:
t=0
Step-by-step explanation:
r=<+1,>
by differentiating the r vector component by component
r' = <2at, 1>
Two vector are orthogonal when the dot product between them is zero, so:
r'·r=0
<+1,>·<2at, 1>=2+2at+t=0
common factor
t(+2a+1)=0
Then, the only real value for t is zero.
-> t=0
3x - y + z = 5 . . . (1)
x + 3y + 3z = -6 . . . (2)
x + 4y - 2z = 12 . . . (3)
From (2), x = -6 - 3y - 3z . . . (4)
Substituting for x in (1) and (3) gives
3(-6 - 3y - 3z) - y + z = 5 => -18 - 9y - 9z - y + z = 5 => -10y - 8z = 23 . . (5)
-6 - 3y - 3z + 4y - 2z = 12 => y - 5z = 18 . . . (6)
(6) x 10 => 10y - 50z = 180 . . . (7)
(5) + (7) => -58z = 203
z = 203/-58 = -3.5
From (6), y - 5(-3.5) = 18 => y = 18 - 17.5 = 0.5
From (4), x = -6 - 3(0.5) - 3(-3.5) = -6 - 1.5 + 10.5 = 3
x = 3, y = 0.5, z = -3.5