4. If DF = 9x - 39, find EF.
Help I’m so confused!!!!
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Answer:
EF =58
Step-by-step explanation:
from the illustration,
EF =DF - DE
given that DF =9x-39 , DE =47 EF=3x +10
substitute them into the formula,
3x +10=9x-39 - 47
solving for x
3x +10 =9x -86
grouping like terms
3x - 9x =-86 -10
-6x=-96
dividing through by -6
[tex] \frac{ - 6x}{ - 6} = \frac{ - 96}{ - 6} [/tex]
[tex]x = \frac{96}{6} [/tex]
[tex]x = 16[/tex]
but EF=3x+10
substitute x=16 into it to get the EF
EF= 3(16)+10
EF=48+10
EF=58
[tex]\huge\boxed{58}[/tex]
First of all, we know that [tex]DE+EF=DF[/tex], because these are two segments that make up one larger segment.
Write this as an equation.
[tex]DE+EF=DF[/tex]
[tex]47+(3x+10)=9x-39[/tex]
Remove the parentheses. [tex]47+3x+10=9x-39[/tex]
Combine the like terms. [tex]3x+57=9x-39[/tex]
Subtract [tex]9x[/tex] from both sides. [tex]-6x+57=-39[/tex]
Subtract [tex]57[/tex] from both sides. [tex]-6x=-96[/tex]
Divide both sides by [tex]-6[/tex]. [tex]x=16[/tex]
Now, find [tex]EF[/tex].
[tex]3x+10[/tex]
[tex]3(16)+10[/tex]
Multiply. [tex]48+10[/tex]
Add. [tex]\boxed{58}[/tex]