Answer:
See below.
Step-by-step explanation:
I will assume that 3n is the last term.
First let n = k, then:
Sum ( k terms) = 7k^2 + 3k
Now, the sum of k+1 terms = 7k^2 + 3k + (k+1) th term
= 7k^2 + 3k + 14(k + 1) - 4
= 7k^2 + 17k + 10
Now 7(k + 1)^2 = 7k^2 +14 k + 7 so
7k^2 + 17k + 10
= 7(k + 1)^2 + 3k + 3
= 7(k + 1)^2 + 3(k + 1)
Which is the formula for the Sum of k terms with the k replaced by k + 1.
Therefore we can say if the sum formula is true for k terms then it is also true for (k + 1) terms.
But the formula is true for 1 term because 7(1)^2 + 3(1) = 10 .
So it must also be true for all subsequent( 2,3 etc) terms.
This completes the proof.
No solution of the system of equations y = -2x + 5 and -5y = 10x + 20 ⇒ 2nd answer
Step-by-step explanation:
Let us revise the types of solutions of a system of linear equations
- One solution
- No solution when the coefficients of x and y in the two equations are equal and the numerical terms are different
- Infinitely many solutions when the coefficients of x , y and the numerical terms are equal in the two equations
∵ y = -2x + 5
- Add 2x to both sides
∴ 2x + y = 5 ⇒ (1)
∵ -5y = 10x + 20
- Subtract 10x from both sides
∴ -10x - 5y = 20
- Divide both sides by -5
∴ 2x + y = -4 ⇒ (2)
∵ The coefficient of x in equation (1) is 2
∵ The coefficient of x in equation (2) is 2
∴ The coefficients of x in the two equations are equal
∵ The coefficient of y in equation (1) is 1
∵ The coefficient of y in equation (2) is 1
∴ The coefficients of y in the two equations are equal
∵ The numerical term in equation (1) is 5
∵ The numerical term in equation (2) is -4
∴ The numerical terms are different
From the 2nd rule above
∴ No solution of the system of equations
No solution of the system of equations y = -2x + 5 and -5y = 10x + 20
Learn more:
You can learn more about the system of equations in brainly.com/question/6075514
#LearnwithBrainly
Answer:
216 people
Step-by-step explanation:
Given:
2.5 feet² is occupied by 1 person
Dimension of room = 216 in × 360 in
Required:
No. of people that would occupy the room
SOLUTION:
Step 1:
Convert the dimensions of the room from in to ft
Note: 1 foot = 12 inches
216 inches = 
360 inches = 
Step 2: calculate area of the room.
Area of the room = 30*18 = 540 ft²
Step 3: calculate the no. of people the room will contain.
2.5 ft² will contain one person
Therefore, 540 ft² will contain: 
Answer:
160 pages.
Step-by-step explanation:
That is 125 - 0.20 * 125
= 125 - 25
= 160 pages.
