Question

Need help. Problem will be inside

Answer 1

The rectangle above has an area of 65 square units. What is the value of x?

Answer 2

A = l x w
A = (x-5)(x+3)
65 = (x-5)(x+3)

Answer 3

okay and what will the next step be? @larryboxaplenty

Answer 4

@larryboxaplenty okay i need help with the next step please

Answer 5

@Compassionate Mind helping please?

Answer 6

foil (x-5)(x+3)

Answer 7

okay so then i get x^2-15x+3x-15

Answer 8

@larryboxaplenty

Answer 9

You need to simplify it more

Answer 10

and it's wrong, you make a mistake somewhere

Answer 11

(x-5)(x+3) = (x*x) + 3x - 5x -15 = x^2-2x-15

Answer 12

@Luigi0210 can you please help me on this problem? i already simplified and everything, but I dont know what's next

Answer 13

@zepdrix

Answer 14

The area is equal to 65,\[\Large\rm 65=x^2-2x-15\]Subtract 65 from each side,\[\Large\rm 0=x^2-2x-80\]Solve for x.

Answer 15

@zepdrix Sorry to bother, you but I don't understand how we will solve for x in this problem,

Answer 16

Also, when I do solve it I get -8 and 10 and those are both an answer choice

Answer 17

Hmm I think this will factor.
We need factors of -80 that are 2 apart from one another.

How about \(\Large\rm 10~and~8\) ?
So one of them needs to be negative to give us -80.
We want to be able to add them to get the -2 in the middle, so we'll let the 10 be negative.
\(\Large\rm -10\cdot8=-80\)
\(\Large\rm -10+8=-2\)

Our polynomial can be factored,\[\Large\rm 0=x^2-2x-80\]\[\Large\rm 0=(x+\text{_})(x+\text{_})\]Where the spaces indicate the factors that we came up with.\[\Large\rm 0=(x-10)(x+8)\]Then you set each factor equal to zero to solve for x in each case,\[\Large\rm 0=(x-10)\]\[\Large\rm x=?\]
\[\Large\rm 0=x+8\]\[\Large\rm x=?\]

Answer 18

After you get your two x values, you have to throw away the one that doesn't make sense.

Answer 19

Okay, so that means the -8 wouldn't make sense because it can't be negative, which means it'll be 10 right?

Answer 20

Yes, good job.

Answer 21

Thank you so much, I appreciate it.

Answer 22

cool c:

Answer 23

You posted this ... 7 days ago?
I can't believe you're still working on it XD lol

Answer 24

lmao yes i am, its summer hw :c