2^3 is equivalent because if you count the number of twos there are in the parentheses its 3.
His work should have looked like this.
2x + y = 5
x − 2y = 10
y = 5 − 2x
x − 2(5 − 2x) = 10
x − 10 + 4x = 10
5x − 10 = 10 When he added in both sides, he subtracted 10 from 10,
5x = 20 instead of adding 10 from 10 to make 20.
x = 4
2(4) + y = 5
8 + y = 5
y = -3
Answer:
d 20.4 years
Step-by-step explanation:
The equation is
A = Pe ^(rt)
We know that r = .034
We want the money to double so A = 2P
Substitute in
2P = P e ^(.034t)
Divide by P
2P/P = P/P e ^(.034t)
2 = e^ (.034t)
Take the natural log on each side
ln (2) = ln(e^ (.034t))
ln (2) = .034t
Divide by .034
ln (2) /.034 = .034t/.034
ln (2)/.034 = t
20.3867 =t
Answer:
a is 2.5
b is 1
gradient is rise over run
