<h3>Answer: 8x+3y = 16</h3>
============================
Work Shown:
x = number of hours spent running
8x = distance he runs (since he runs at 8 mph)
y = number of hours spent walking
3y = distance he walks (he walks at a speed of 3 mph)
8x+3y = total distance = 16 miles
8x+3y = 16
This equation is in standard form Ax+By = C
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Extra Info
Solving for y will get
8x+3y = 16
3y = -8x+16
y = (-8x+16)/3
y = (-8x)/3+16/3
y = (-8/3)x+16/3
This is in slope intercept form y = mx+b
m = -8/3 is the slope
b = 16/3 is the y intercept
i)On z, define a∗b=a−b
here aϵz
+
and bϵz
+
i.e.,a and b are positive integers
Let a=2,b=5⇒2∗5=2−5=−3
But −3 is not a positive integer
i.e., −3∈
/
z
+
hence,∗ is not a binary operation.
ii)On Q,define a∗b=ab−1
Check commutative
∗ is commutative if,a∗b=b∗a
a∗b=ab+1;a∗b=ab+1=ab+1
Since a∗b=b∗aforalla,bϵQ
∗ is commutative.
Check associative
∗ is associative if (a∗b)∗c=a∗(b∗c)
(a∗b)∗c=(ab+1)∗c=(ab+1)c+1=abc+c+1
a∗(b∗c)=a∗(bc+1)=a(bc+1)+1=abc+a+1
Since (a∗b)∗c
=a∗(b∗c)
∗ is not an associative binary operation.
iii)On Q,define a∗b=
2
ab
Check commutative
∗ is commutative is a∗b=b∗a
a∗b=
2
ab
b∗a=
2
ba
=
2
ab
a∗b=b∗a∀a,bϵQ
∗ is commutativve.
Check associative
∗ is associative if (a∗b)∗c=a∗(b∗c)
(a∗b)∗c=
2
(
2
ab
)∗c
=
4
abc
(a∗b)∗c=a∗(b∗c)=
2
a×
2
bc
=
4
abc
Since (a∗b)∗c=a∗(b∗c)∀a,b,cϵQ
∗ is an associative binary operation.
iv)On z
+
, define if a∗b=b∗a
a∗b=2
ab
b∗a=2
ba
=2
ab
Since a∗b=b∗a∀a,b,cϵz
+
∗ is commutative.
Check associative.
∗ is associative if $$
(a∗b)∗c=a∗(b∗c)
(a∗b)∗c=(2
ab
)
∗
c=2
2
ab
c
a∗(b∗c)=a∗(2
ab
)=2
a2
bc
Since (a∗b)∗c
=a∗(b∗c)
∗ is not an associative binary operation.
v)On z
+
define a∗b=a
b
a∗b=a
b
,b∗a=b
a
⇒a∗b
=b∗a
∗ is not commutative.
Check associative
∗ is associative if $$
(a∗b)∗c=a∗(b∗c)
(a∗b)∗c=(a
b
)
∗
c=(a
b
)
c
a∗(b∗c)=a∗(2
bc
)=2
a2
bc
eg:−Leta=2,b=3 and c=4
(a∗b)
∗
c=(2∗3)
∗
4=(2
3
)
∗
4=8∗4=8
4
a∗(b∗c)=2
∗
(3∗4)=2
∗
(3
4
)=2∗81=2
81
Since (a∗b)∗c
=a∗(b∗c)
∗ is not an associative binary operation.
vi)On R−{−1}, define a∗b=
b+1
a
Check commutative
∗ is commutative if a∗b=b∗a
a∗b=
b+1
a
b∗a=
a+1
b
Since a∗b
=b∗a
∗ is not commutatie.
Check associative
∗ is associative if (a∗b)∗c=a∗(b∗c)
(a∗b)∗c=(
b+1
a
)
∗
c=
c
b
a
+1
=
c(b+1)
a
a∗(b∗c)=a∗(
c+1
b
)=
c+1
b
a
=
b
a(c+1)
Since (a∗b)∗c
=a∗(b∗c)
∗ is not a associative binary operation
Area by Heron's formula:
semiperimeter = (15 + 20 + 25)/2 = 60/2 = 30 cm
The formula of the area of a triangle: Area = 1/2 * base * height
1/2 * 25 * height = 150
12.5 * height = 150
height = 150/12.5
height = 12 cm
Answer:
Call the sister's height x. The boy is twice as tall, so that's 2x. The father is 30 cm taller than the boy, so his height is 2x + 30. The combined height is 3.8m, which is 380cm. Now you can write an equation
x + 2x + 2x + 30 = 380
collect like terms
5x = 350
x = 70
the sister is 70cm tall, the boy is 2*70 = 140 cm, and the father is 140 + 30 = 170cm
Check that the heights add up to 3.8m: 70 + 140 + 170 = 380 cm = 3.8m. Correct
Step-by-step explanation:
hope it helps
