Given :-
- a² - 2a - b² = 0
- 2b + 2ab = 0
To find :-
Solution :-
<u>Taking</u><u> </u><u>second</u><u> </u><u>equation</u><u>:</u><u>-</u>
- 2b + 2ab = 0
- 2b ( 1 + a ) = 0
- 2b = 0 or (1+a) = 0
- b = 0 , a = -1
<u>Substitute</u><u> </u><u>in </u><u>first </u><u>equation</u><u> </u><u>:</u><u>-</u><u> </u>
<u>When </u><u>b </u><u>=</u><u> </u><u>0</u><u> </u><u>,</u>
- a² - 2a - 0² = 0
- a² - a = 0
- a( a -1) =0
- a = 0 , 1
<u>When </u><u>a </u><u>=</u><u> </u><u>-</u><u>1</u><u> </u><u>,</u>
- (-1)² - 2*(-1) - b² = 0
- 1 + 2 - b² = 0
- b² = 3
- b = ±√3
<u>Answer </u><u>:</u><u>-</u><u> </u>
- a = 0,1 ; b = 0
- a = -1 , b = ±√3
Answer:
a. closed under addition and multiplication
b. not closed under addition but closed under multiplication.
c. not closed under addition and multiplication
d. closed under addition and multiplication
e. not closed under addition but closed under multiplication
Step-by-step explanation:
a.
Let A be a set of all integers divisible by 5.
Let
∈A such that 
Find 

So,
is divisible by 5.

So,
is divisible by 5.
Therefore, A is closed under addition and multiplication.
b.
Let A = { 2n +1 | n ∈ Z}
Let
∈A such that
where m, n ∈ Z.
Find 

So,
∉ A

So,
∈ A
Therefore, A is not closed under addition but A is closed under multiplication.
c.

Let
but
∉A
Also,
∉A
Therefore, A is not closed under addition and multiplication.
d.
Let A = { 17n: n∈Z}
Let
∈ A such that 
Find x + y and xy


So,
∈ A
Therefore, A is closed under addition and multiplication.
e.
Let A be the set of nonzero real numbers.
Let
∈ A such that 
Find x + y

So,
∈ A
Also, if x and y are two nonzero real numbers then xy is also a non-zero real number.
Therefore, A is not closed under addition but A is closed under multiplication.
Answer: $7,500
Step-by-step explanation:
Use the formula: SI = P(1 + rt)
SI = 5000(1 + 0.05[10])
SI = 5000 + 2500
SI = $7,500
After 10 years, your balance should be $7,500
if there were 100 questions then 76 were correct, and 24 incorrect, you can simplify and rearrange the fraction depending on how many questions there were,
For compound interest, the formula is given below:
Amount = 
Here, P = 18,800
n = 2
r = 13/100
So, Amount = 

= 18,800 × 1.2769
= 24005.72
Compound Interest = Amount - Principal
Compound Interest = 24005.72 - 18800
= 5205.72
Hence, the compound interest for Rs.18,800, calculated for 2 years at 13% rate of interest compounded annually is Rs.5205.72.