The area of a rectangle is given by A = x2 + 4x – 5. Find the value of x if the total area of the rectangle is equal to 7 square units.
a) x = 7
b) x = 5
c) x = 1
d) x = 2

Question

The area of a rectangle is given by A = x2 + 4x – 5. Find the value of x if the total area of the rectangle is equal to 7 square units.
	a)	 x = 7
	b)	x = 5
	c)	 x = 1
	d)	x = 2

terenzreignz · Answer

The best way to start these is to put down what we're given...
What do we know so far?

terenzreignz · Answer

We know that the area of the rectangle is 7 right?
What else do we know?

terenzreignz · Answer

Work with me here, you should be able to get to the answer by yourself...

this · Answer

ya im trying

terenzreignz · Answer

so, We know that A = 7
Therefore... we can substitute 7 for A in the first equation... what do we get?

terenzreignz · Answer

Ok, so we know that A = 7 right?
Therefore....
7 = x^2 + 4x - 5, 
do you get why?

this · Answer

o yes

terenzreignz · Answer

Can you solve Quadratic equations?

this · Answer

hun not really

terenzreignz · Answer

so we have 7 = x^2 + 4x - 5
What I want you to do is manipulate this equation so that there is a 0 on one side.

terenzreignz · Answer

It's actually simple :)
All you have to do is add (-7) to both sides of the equation 
go ahead, try it, and show me what you got.

this · Answer

x^2+4x-12

this · Answer

im not sure just trying ;)

terenzreignz · Answer

yes, but that was not an equation, but close enough:
x^2 + 4x - 12 = 0
Can you do it from here?

this · Answer

yes let me try

this · Answer

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