Multiplication and distributive property are your friends for this problen
Answer:
Step-by-step explanation:
Eight
590 = 1800 e^(-0.4t) Divide by 1800
0.32778 = e^(-0.4t) Put the value for e in the denominator.
0.32778 = 1 / e^(0.4t) Notice the sign's gone. Multiply both sides by e^(0.4t)
0.32778 *e^(0.4t) = 1 Divide by 0.32778
e^(0.4t) = 3.0508 Take the natural log of both sides.
0.4t = 1.11542 Divide both sides by 0.4
t = 2.78855
You should put this in the original equation to see if it checks. It does.
=============================
Nine
3^(3 - 3x) + 6 = 42 Subtract 6 from both sides
3^(3 - 3x) = 36 Take the log of both sides.
(3 - 3x) ln(3) = ln 36
(3 - 3x) *1.098612 = 3.58352 Divide by 1.098612
3 - 3x = 3.26186 Subtract 3 from both sides
- 3x = 0.26186 Divide by - 3
x = - 0.087287
Andrea drove 50miles/hour
refer to pic for working
1: Solve for either x or y in one of the equations. So x + y = -1 is y = -x -1
2: substitute the new equation in the opposite equation. So x - (-x - 1) = 7
3: distribute the negative. X + x + 1 = 7
4: combine like terms. 2x + 1 = 7
5: solve for x. Subtract 1 on both sides. 2x = 6
6: divide by 2 to get x by itself. X = 3
7: plug the new value of x into one of the ORIGINAL equations. 3 + y = -1
8: solve for y. Subtract 3 on both sides.
Y = -4
9: the solution is written as (x,y) so the solution would be (3, -4)