Let's say X is the first brother's age
x+2 is second brother, and x+4 is the third brother
Since the product of the first and third boy x(x+4) is 20 more than twice (20+x(x+2), our equation is x(x+4)=20+2(x+2)
Simplify from there and see what you get.
18 months
……33inches, weight 25.5 pounds
When
he was born = 9 months…20 inches, weight 8, 4 pounds
Every
9 months his height growth is 33-20 = 13 inches, his weight is 25.5-8.4=17.1 pounds
<span>Pounds. This means, for every 9 months, his growth is
13 inches and his weight is 17.1 pounds. For example we can determine his
growth in 3 years.</span>
<span>3
years = 36 months, 36= 9*4, his height will be 4*13 inches= 52 inches, his
weight will be 4*17.1 = 68.4 pounds </span>
Let
x---------------> distance from people living to the city center
we Know that
Zone 1 covers people living within three miles of the city center
Zone 1 ------------> [x < 3 miles]
Zone 2 covers those between three and seven miles from the center
Zone 2 ------------> [ 3 <= x < = 7 miles]
Zone 3 covers those over seven miles from the center
Zone 3 ------------> [ x > 7 miles]
<span>calculate the distance between two points to find the value of x
</span>
case A) point (0,0) point (3,4)
x=√[(y2-y1)² +(x2-x1)²]----------> √[(4-0)² +(3-0)²]------> √[16+9]
x=√25-------------> x=5 miles
the answer Part A)
people living in (3,4)
x=5 miles -------------> covers Zone 2 [ 3 < =x <= 7 miles]
case B) point (0,0) point (6,5)
x=√[(y2-y1)² +(x2-x1)²]----------> √[(5-0)² +(6-0)²]------> √[25+36]
x=√61-------------> x=7.81 miles
the answer Part B)
people living in (6,5)
x=7.81 miles -------------> covers Zone 3 [ x > 7 miles]
case C) point (0,0) point (1,2)
x=√[(y2-y1)² +(x2-x1)²]----------> √[(2-0)² +(1-0)²]------> √[4+1]
x=√5-------------> x=2.23 miles
the answer Part C)
people living in (1,2)
x=2.23 miles -------------> covers Zone 1 [ x < 3 miles]
case D) point (0,0) point (0,3)
x=√[(y2-y1)² +(x2-x1)²]----------> √[(3-0)² +(0-0)²]------> √[9]
x=√9-------------> x=3 miles
the answer Part D)
people living in (0,3)
x=3 miles -------------> covers Zone 2 [ 3 < =x <= 7 miles]
case E) point (0,0) point (1,6)
x=√[(y2-y1)² +(x2-x1)²]----------> √[(6-0)² +(1-0)²]------> √[36+1]
x=√37-------------> x=6.08 miles
the answer Part E)
people living in (1,6)
x=6.08 miles -------------> covers Zone 2 [ 3 < = x <= 7 miles]
7) Certainly there is a typo in the statement, just see that the expression of item (ii) is different from that of item (i). Probably the correct expression is:
. With this consideration, we can continue.
(i) Let E the expression that we are analyzing:
Since (x-1)² is a perfect square, it is a positive number. So, E is a result of a sum of two positive numbers, 2(x-1)² and 3. Hence, E is a positive number, too.
(ii) Manipulating the expression:
So, it's the case when E=0. However, E is always a positive number. Then, there is no real number x that satisfies the expression.
8) Let E the expression that we want to calculate:
Multiplying by (2-1) in the both sides:
Repeating the process, we obtain:
