Download Math 31 Answers to Quiz 2

Math 31
(1)
Evaluating:
=⇒
(2)
for x = −2 and y = −5
−5x + 3y − 2 = −5(−2) + 3(−5) − 2 = 10 + (−15) + (−2) = 10 + (−17) = −7
Evaluating:
=⇒
−5x + 3y − 2
Answers to Quiz 2
3x2 − x − 5
for x = −0.3
2
2
3x − x − 5 = 3(−0.3) − (−0.3) − 5 = 3(0.09) + 0.3 − 5 = 0.27 + 0.3 − 5
= 0.57 − 5 = 0.57 + (−5) = −4.43
(3)
Solve the equation for x:
x − 16 = −5
Move −16 to the right hand side (or, add 16 to both sides):
=⇒
(4)
x = −5 + 16 = 11
Solve the equation for x:
−x + 8 = 27
More 8 to the right hand side (or, add (−8) to both sides):
=⇒
−x = 27 − 8
=⇒
−x = 19
Divide both sides by (−1)
(5)
=⇒
Solve the equation for x:
x = −19
6x + 7 = −1 + 5x
Move 7 to the right hand side and 5x to the left:
=⇒
(6)
6x − 5x = −1 − 7
=⇒
Solve the equation for x:
x = −8
−0.9x = −72
Divide both sides by (−0.9)
=⇒
x = 80
Or, multiply both sides by 10 to change to coefficient to an integer first,
=⇒
(7)
(10)(−0.9x) = (10)(−72)
=⇒
−9x = −720
=⇒
−720
−9
x=
= 80
− 53 x = 12
Solve the equation for x:
Multiply both sides by 5 (the LCD) to eliminate the denominator:
=⇒
−3x = 60
Divide both sides by (−3)
(8)
=⇒
4x
5
Solve the equation for x:
x = −20
=
6
7
Multiply both sides by the LCD 35:
Divide both sides by 28:
(9)
=⇒
Solve the equation for x:
=⇒
x=
30
28
=
28x = 30
15
14
7x − 9x − 11 = 25 − 6x − 4
Simplify both sides first, (by combining like terms:)
=⇒
−2x − 11 = 21 − 6x
move −11 to the right hand side and move −6x to the left:
=⇒
−2x + 6x = 21 + 11
Divide both side by 4
(10)
=⇒
=⇒
x=
Solve the equation for x:
Simplify both side first,
4x = 32
32
4
=8
18 + 5(2x − 3) = x − 3(4 + 2x)
=⇒
18 + 10x − 15 = x − 12 − 6x
Move 3 to the right hand side and −5x to the left:
10x + 5x = −12 − 3
=⇒
Divide both sides by 15
15x = −15
=⇒
x = −1
=⇒
3 + 10x = −5x − 12
(11)
Solve the equation for x:
5x − 4(x − 9) = 2x − 3
Simplify both sides first:
=⇒
5x − 4x + 36 = 2x − 3
=⇒
x + 36 = 2x − 3
Move 36 to the right hand side and 2x to the left:
=⇒
x − 2x = −3 − 36
=⇒
−x = −39
Divide both sides by (−1)
=⇒
x = 39
(12)
x
4
Solve the equation for x:
−
x
3
= 18
Multiply both sides by the LCD 12 to eliminate all the denominators:
=⇒
3x − 4x = 216
=⇒
Divide both sides by −1
(13)
−x = 216
=⇒
Solve the equation for x:
x = −216
3x
5
−1 = x2
Multiply both sides by the LCD 10 to eliminate all the denominators:
=⇒
6x − 10 = 5x
Move −10 to the right hand side and 5x to the left:
=⇒
(14)
6x − 5x = 10
=⇒
Solve the equation for x:
x = 10
=6−x
5− 3x+1
4
Multiply both sides by the LCD 4 to eliminate the denominators:
=⇒
(4)5 − (4)( 3x+1
) = (4)6 − (4)x
4
=⇒
20 − (3x + 1) = 24 − 4x
=⇒
20 − 3x − 1 = 24 − 4x
Move 19 to the right and −4x to the left:
=⇒
=⇒
−3x + 4x = 24 − 19
19 − 3x = 24 − 4x
=⇒
x=5