Okay so the area of a rectangle x by y with a border of width b will be:
A=(x+2b)(y+2b)
A=xy+2bx+2by+4b^2 we are told that A=320, x=11, and y=15 so now we have:
320=165+22x+30x+4x^2, now I am using x as the border width...
4x^2+55x+165=320 is the equation that they listed..
...
4x^2+55x-155=0 using the quadratic formula for efficiency...
x=(-55±√5505)/8 since x>0
x≈2.399 which for some unknown (incorrect) reason they rounded to
x=2.5
So in short, your answer is a)
(btw if i write 4x^3 it means 4x to the power of 3)
1) (2x+3)(x-2)
2x^2 -4x + 3x -6
2x^2 -x -6
2) x^2 +10x +24
(x+12)(x-2)
3) 6x^2 -13x +6
(2x )(3x ) not sure on this one
4) x^2 +8x +15
(x+3)(x+5)
x= -3 x=-5
5) x^2 -4x -45
(x+5) (x-9)
x=-5 x=9
hope this helps, if you need any help understanding what happens just ask
Answer:
x = 7.6
Step-by-step explanation:
We know the opposite side and the adj side and this is a right triangle
tan theta = opp / adj
tan 66 = 17/x
x tan 66 = 17
x = 17 /tan 66
x=7.56888
To the nearest tenth
x = 7.6