Factor 125x3 + 343y3

Mathematics

1 answer:

Annette [7]1 year ago

5 0

Answer:

(5x + 7y)(25x² - 35xy + 49y²)

Step-by-step explanation:

125x³ + 343y³ ← is a sum of cubes and factors in general as

a³ + b³ = (a + b)(a² - ab + b² )

125x³ = (5x)³ ⇒ a = 5x

343y³ = (7y)³ ⇒ b = 7y

125x³ + 343y³

= (5x + 7y)((5x)² - (5x × 7y) + (7y)²)

= (5x + 7y)(25x² - 35xy + 49y²) ← in factored form

You might be interested in

The local grocery store wants to know if the shoppers prefer Crest or Colgate toothpaste. The store gives all of its shoppers a

ch4aika [34]

i think the answer is letter C

5 0

2 years ago

-3^(-x)-6=-3^x+10<br><br>Solve the equation below for x by graphing plz

vitfil [10]

To graph it, just graph $y=-3^{-x}-6$ and $y=-3^x+10$ and see where they intersect

I would like to solve it by using math and not graphing
if you don't want to see the math, just don't scroll down
the graphical meathod is above, first line, just read it

hmm
multiply both sides by -1
$3^{-x}+6=3^x-10$
multiply both sides by $3^x$
$3^0+6(3^x)=3^{2x}-10(3^x)$
$1+6(3^x)=3^{2x}-10(3^x)$
minus 1 from both sides and minus 6(3^x) from both sides
$0=3^{2x}-16(3^x)-1$
use u subsitution
$u=3^x$
we can rewrite it as
$0=u^2-16u-1$
now factor
I mean use quadratic formula
for $ax^2+bx+c=0$ $x=\frac{-b+/-\sqrt{b^2-4ac}}{2a}$
so for 0=u^2-16u-1, a=1, b=-16, c=-1
$u=\frac{-(-16)+/-\sqrt{(-16)^2-4(1)(-1)}{2(1)}$
$u=8+/-\sqrt{65}$
remember that u=3^x so u>0
if we have u=8+√65, it's fine, but u=8-√65 is negative and not allowed
so therfor
$u=8+\sqrt{65}=3^x$
$8+\sqrt{65}=3^x$
if you take the log base 3 of both sides you get
$log_3(8+\sqrt{65})=x$
if you use ln then
$ln(8+\sqrt{65})=xln(3)$
then
$\frac{ln(8+\sqrt{65})}{ln(3)}=x$