Sagot :
We have A=228,980 and P=200,000
A = P(1+r)²
228,980 = 200,000(1+r)²
228,980 = 200,000(r²+2r+1)
228,980 = 200,000r² + 400,000r + 200,000
0 = 200,000r² + 400,000r - 28,980
0 = 10,000 r² + 20,000r - 1,449
We then use the quadratic formula:
r = -20,000 ± √(20,000²+4·10,000·1449) = -20,000 ± √457960000
2(10,000) 20,000)
= -20,000 ± 21,400 = -100 ± 107 = -207/100 or 7/100
20,000 100
We take the positive rate which is 7%. So r=7%.
A = P(1+r)²
228,980 = 200,000(1+r)²
228,980 = 200,000(r²+2r+1)
228,980 = 200,000r² + 400,000r + 200,000
0 = 200,000r² + 400,000r - 28,980
0 = 10,000 r² + 20,000r - 1,449
We then use the quadratic formula:
r = -20,000 ± √(20,000²+4·10,000·1449) = -20,000 ± √457960000
2(10,000) 20,000)
= -20,000 ± 21,400 = -100 ± 107 = -207/100 or 7/100
20,000 100
We take the positive rate which is 7%. So r=7%.
Hmm, now I can post the solution here I have posted in the comment section ten hours ago (check above).
A= 228, 980
P= 200, 000
r = rate
228,980 = 200,000 (1 + r)²
228,980 = 200 000 (1 + 2r + r²)
228,980 = 200 000 + 400 000 r + 200 000r²
200 000 r² + 400 000 r + 200 000 - 228 980 = 0
2000 000 r² + 400 000 r -28 980 = 0
Factor or use the quadratic formula:
( x - 7/100 ) (x + 207/100) = 0
x = 7/100 or x = -207/100
Choose the positive root, x-value: 7/100
7/100 = 0.07 = 7 percent
The rate is 7 %
A= 228, 980
P= 200, 000
r = rate
228,980 = 200,000 (1 + r)²
228,980 = 200 000 (1 + 2r + r²)
228,980 = 200 000 + 400 000 r + 200 000r²
200 000 r² + 400 000 r + 200 000 - 228 980 = 0
2000 000 r² + 400 000 r -28 980 = 0
Factor or use the quadratic formula:
( x - 7/100 ) (x + 207/100) = 0
x = 7/100 or x = -207/100
Choose the positive root, x-value: 7/100
7/100 = 0.07 = 7 percent
The rate is 7 %