Answer:
v = 7
is the value for which
x = (-21 - √301)/10
is a solution to the quadratic equation
5x² + 21x + v = 0
Step-by-step explanation:
Given that
x = (-21 - √301)/10 .....................(1)
is a root of the quadratic equation
5x² + 21x + v = 0 ........................(2)
We want to find the value of v foe which the equation is true.
Consider the quadratic formula
x = [-b ± √(b² - 4av)]/2a ..................(3)
Comparing (3) with (2), notice that
b = 21
2a = 10
=> a = 10/2 = 5
and
b² - 4av = 301
=> 21² - 4(5)v = 301
-20v = 301 - 441
-20v = -140
v = -140/(-20)
v = 7
That is a = 5, b = 21, and v = 7
The equation is then
5x² + 21x + 7 = 0
Since the length of this rectangle is twice its breadth, the length is equal to 40 cm.
<h3>How to calculate the area of a rectangle?</h3>
Mathematically, the area of a rectangle can be calculated by using this formula:
Area = Length × Width
Based on the information provided, we have:
- Its length is decreased half of the 10 cm ⇒ (length - 5)
- Its breadth is increased by half of the 10 cm ⇒ (breadth + 5)
- Its area is increased by 75 cm ⇒ (area + 5)
Substituting the parameters into the formula, we have:
LB + 75 = (L - 5)(B + 5)
2B² + 75 = (2B - 5)(2B + 5)
2B² + 75 = 2B(B + 5) - 5(B + 5)
2B² + 75 = 2B² + 10B - 5B - 25
5B = 75 + 25
5B = 100
B = 100/20
B = 20 cm.
For the length, we have:
L = 2B
L = 2 × 20
L = 40 cm.
Read more on rectangle here: brainly.com/question/25292087
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She walked 2.808 miles.
0.72 seconds ==> 0.00078 miles
0.72 minutes ==> 0.0468 miles
0.72 hours ==> 2.808 miles
Hope that helped.
