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anonymous
 4 years ago
Lenght of rectangle is 7 cm less than 4 times its width. Area is 36, find dimensions. Is this set up right? : 4x7=36
anonymous
 4 years ago
Lenght of rectangle is 7 cm less than 4 times its width. Area is 36, find dimensions. Is this set up right? : 4x7=36

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asnaseer
 4 years ago
Best ResponseYou've already chosen the best response.2not quite  the question says that the length is 7cm less than 4 times its width, so if we call the length y and the width x, then you can write: y = 4x  7 It also says the area is 36, so we know the area of a rectangle is length times width, therefore: xy = 36 Now you have two equations with two unknowns so you should be able to solve this to find x and y.

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0What do you mean by that? How can i set it up to solve?

asnaseer
 4 years ago
Best ResponseYou've already chosen the best response.2substitute the expression for y from the first equation into the second equation. that will give you a quadratic equation in x to solve.

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0ok be right back.. :)

asnaseer
 4 years ago
Best ResponseYou've already chosen the best response.2the question was asking for the dimensions of the rectangle  so you need an answer for x and y.

asnaseer
 4 years ago
Best ResponseYou've already chosen the best response.2so how did you get 165?

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0i put it into the top equation the area

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0The length of a rectanlge is 7 cm less than 4 times its width. Its area is 36, find dimensions

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0I put it down here to make it easier for you

asnaseer
 4 years ago
Best ResponseYou've already chosen the best response.2we have two equations:\[y=4x7\tag{a}\]and:\[xy=36\tag{b}\]if we substitute the expression for y from equation (a) into equation (b) we get:\[x(4x7)=36\]\[4x^27x=36\]\[4x^27x36=0\]this is a quadratic equation which you should be able to factor (or use the quadratic equation formula) to find the two possible answers for x.

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0do i use bottom equation to solve now :D and two ( ) are my answer? :D

asnaseer
 4 years ago
Best ResponseYou've already chosen the best response.2you need to solve:\[4x^27x36=0\]this will give you two possible answers for x. one will be a positive value and the other will be a negative value. since a rectangle cannot have a negative length you can reject the negative solution. you will therefore be left with one answer for x. plug this value of x back into equation (a) above to find the corresponding value for y. that will then give you the dimensions of the rectangle.

asnaseer
 4 years ago
Best ResponseYou've already chosen the best response.2correct values for x: now you can reject the negative value as I stated above.

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0so i take out negative so its only 9/4

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0is the answer 4 and 9?

asnaseer
 4 years ago
Best ResponseYou've already chosen the best response.2no. the quadratic equation gave you two possible solutions for x. one of these was x=4 and the other was x=9/4. since a rectangle cannot have a negative length, you can reject the solution x=9/4. you are therefore left with x=4 as the only valid solution for the width of the rectangle. plug this value of x into equation (a) above to get the correct valid value for the length y of the rectangle.

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0I think i understand now but can you give me the answer? :( I wont ask again, its just this stupid program im using keeps knocking me off and giving me new questions, the server is freaking out and if i leave it sitting for awhile trying to figure it out it makes me start over, which is unfair

asnaseer
 4 years ago
Best ResponseYou've already chosen the best response.2the last step is very easy  you should be able to calculate it yourself.

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0what do i substitute 4 into again?

asnaseer
 4 years ago
Best ResponseYou've already chosen the best response.2substitute x=4 into: y = 4x  7

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0so its y=4(4)7? gets y

asnaseer
 4 years ago
Best ResponseYou've already chosen the best response.2yes, so length of rectangle is 9 and width is 4
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