Step-by-step explanation:
0.75a + 2(0.90) = 27.60
is the correct answer
![\bf \textit{difference and sum of cubes} \\\\ a^3+b^3 = (a+b)(a^2-ab+b^2) \\\\ a^3-b^3 = (a-b)(a^2+ab+b^2) \\\\[-0.35em] \rule{34em}{0.25pt}\\\\ \begin{cases} 729=27^2\\ \qquad (3^3)^2\\ 1000=10^3 \end{cases}\implies 729^{15}+1000\implies ((3^3)^2)^{15}+10^3 \\\\\\ ((3^2)^{15})^3+10^3\implies (3^{30})^3+10^3\implies (3^{30}+10)~~[(3^{30})^2-(3^{30})(10)+10^2] \\\\\\ (3^{30})^3+10^3\implies (3^{30}+10)~~~~[(3^{60})-(3^{30})(10)+10^2]](https://tex.z-dn.net/?f=%5Cbf%20%5Ctextit%7Bdifference%20and%20sum%20of%20cubes%7D%20%5C%5C%5C%5C%20a%5E3%2Bb%5E3%20%3D%20%28a%2Bb%29%28a%5E2-ab%2Bb%5E2%29%20%5C%5C%5C%5C%20a%5E3-b%5E3%20%3D%20%28a-b%29%28a%5E2%2Bab%2Bb%5E2%29%20%5C%5C%5C%5C%5B-0.35em%5D%20%5Crule%7B34em%7D%7B0.25pt%7D%5C%5C%5C%5C%20%5Cbegin%7Bcases%7D%20729%3D27%5E2%5C%5C%20%5Cqquad%20%283%5E3%29%5E2%5C%5C%201000%3D10%5E3%20%5Cend%7Bcases%7D%5Cimplies%20729%5E%7B15%7D%2B1000%5Cimplies%20%28%283%5E3%29%5E2%29%5E%7B15%7D%2B10%5E3%20%5C%5C%5C%5C%5C%5C%20%28%283%5E2%29%5E%7B15%7D%29%5E3%2B10%5E3%5Cimplies%20%283%5E%7B30%7D%29%5E3%2B10%5E3%5Cimplies%20%283%5E%7B30%7D%2B10%29~~%5B%283%5E%7B30%7D%29%5E2-%283%5E%7B30%7D%29%2810%29%2B10%5E2%5D%20%5C%5C%5C%5C%5C%5C%20%283%5E%7B30%7D%29%5E3%2B10%5E3%5Cimplies%20%283%5E%7B30%7D%2B10%29~~~~%5B%283%5E%7B60%7D%29-%283%5E%7B30%7D%29%2810%29%2B10%5E2%5D)
now, we could expand them, but there's no need, since it's just factoring.
f(x)=x3−5
Replace f(x)
with y
.
y=x3−5
Interchange the variables.
x=y3−5
Solve for y
.
Since y
is on the right side of the equation, switch the sides so it is on the left side of the equation.
y3−5=x
Add 5
to both sides of the equation.
y3=5+x
Take the cube root of both sides of the equation to eliminate the exponent on the left side.
y=3√5+x
Solve for y
and replace with f−1(x)
.
Replace the y
with f−1(x)
to show the final answer.
f−1(x)=3√5+x
Set up the composite result function.
f(g(x))
Evaluate f(g(x))
by substituting in the value of g into f
.
(3√5+x)3−5
Simplify each term.
Remove parentheses around 3√5+x
.
f(3√5+x)=3√5+x3−5
Rewrite 3√5+x3
as 5+x
.
f(3√5+x)=5+x−5
Simplify by subtracting numbers.
.
Subtract 5
from 5
.
f(3√5+x)=x+0
Add x
and 0
.
f(3√5+x)=x
Since f(g(x))=x
, f−1(x)=3√5+x is the inverse of f(x)=x3−5
.
f−1(x)=3√5+x
Use pythagorean theorem - a^2+ b^2 = c^2
a = 2ft, b = ?, c = 6ft
2 x 2 + b^2 = 6 x 6
4 + b^2 = 36
b^2 = 36 - 4 = 32
b = square root of 32
= 5.66ft
Answer: 231
<u>Explanation:</u>
Liwen Celina
5x 6x
5x - 21 = 
6x
5x - 21 = 4x
<u>-4x +21</u> <u>-4x +21 </u>
x = 21
Liwen: 5x = 5(21) = 105
Celina: 6x = 6(21) =<u> 126</u>
Total: 231
