John's effective annual rate is about
(1 +.0576/4)^4 -1 ≈ 5.8856%
According to the "rule of 72", John's money will have doubled in
72/5.8856 = 12.23 years
John's balance will be $4500 in 1989.
_____
Since you're only concerned with the year (not the month), you don't actually need to determine the effective annual rate. The given rate of 5.76% will tell you 72/5.76 = 12.5 years. The actual doubling time is closer to 12.12 years, so using the effective rate gives results that are closer, but "good enough" is good enough in this case.
-19
Explanation: 22-41=-19
Answer:
2/7(x-2)=4x
(2×x-2×2)/7 = 4x
(2x-4)/7 = 4x
2x-4×(1) = 4x × 7 ( Cross multiply)
2x-4 = 28
2x = 32
2x÷2 = 32÷2
x=16
Answer:4x^2 +28x +49=(2x +7)^2
Step-by-step explanation:
a2±2ab+b2=(a±b)2
In this case
a=2x and b=7 ...
4x2+28x+49=(2x)2+(2⋅
(2x)⋅
7)+72=(2x+7)2
