I can't understand this problem. I would apperciate some help, I can understand how time is so evaggerating. But help would be appreciated.
2006-10-25 15:23:23 · 8 answers · asked by Lizzie 5 in Science & Mathematics ➔ Mathematics
Notice that your question does not say what the length of the width is, right? We can call the width xcm.
The length is 7cm more than the width.
So, length = xcm + 7cm.
NOTE: The word more means to add in math.
The perimeter = 78cm.
To find the rectangle's dimensions means to find the length and width.
We can use the formula:
Perimeter = 2 times length + 2 times width or simply:
P = 2L + 2w
What is our perimeter?...78cm.
What is our width?...xcm.
What is our length?... xcm + 7cm.
Plug that information into the formula and simplify.
NOTE: I will not use the cm until the end of the problem. Get it?
78 = 2x + 2(x+7)
78 = 2x + 2x + 14
78 = 4x + 14
78 - 14 = 4x
64 = 4x
16 = x
Now that we know the value of x, we plug 16 into the width and length.
Since width = xcm and we just found x to be 16, our width is 16cm.
Our length is xcm + 7cm. Replacing x by 16, we get
16cm + 7cm = 23cm.
Final answers: Width = 16cm and length = 23cm.
Guido
2006-10-25 15:37:45 · answer #1 · answered by Anonymous · 0⤊ 0⤋
Let the width be 'x' and the length be 'x + 7'
The two lengths are x + 7 and the two widths are x
Perimeter = 78
Perimeter = The two lengths + the two widths
78 = (x + 7) + (x + 7) + x + x
78 = x + x + x + x +7 +7
78 = 4x + 14
4x = 78 - 14
= 64
x = 64/4
x = 16
The two widths are 16cm
Length = Width + 7 = 16 + 7 = 23
The dimensions of the rectangle are 23 by 16 cm
2006-10-26 04:14:36 · answer #2 · answered by Akilesh - Internet Undertaker 7 · 1⤊ 0⤋
L= w+7
P=78=2L+2w
P=78=2(w+7)+2w
78= 2w+14+2w=4w+14
4w=78-14=64
w=64/4=16
so the width is 16 and since length is width plus 7, length is 16+7 which is 23
2006-10-25 15:32:19 · answer #3 · answered by Anonymous · 0⤊ 0⤋
P = 2(l + w)
l = w + 7
78 = 2((w + 7) + w)
78 = 2(w + 7 + w)
78 = 2(2w + 7)
39 = 2w + 7
2w = 32
w = 16
l = 16 + 7 = 23
ANS :
width = 16cm
length = 23 cm
2006-10-25 15:41:16 · answer #4 · answered by Sherman81 6 · 1⤊ 0⤋
L = length
W = width
P = Perimeter
P = 2L + 2W
L = W + 7cm
Substitute the L for W in the first equation
P= 2(W-8) + 2W
since we know p = 78, solve for W
78 = 2W + 14 + 2W
W = 16 cm
therfore:
L = 23 + 7 = 23 cm
2006-10-25 15:30:28 · answer #5 · answered by crookmatt 4 · 1⤊ 0⤋
__________
I I
I_________ I width: x
length: x+7
perimeter: sum of all the sides
perimeter = x+x+x+7+x+7 = 78
4x = 78 - 7 - 7
4x = 64
x = 64/4
x = 16
width is 16
length is 16+7 = 23
2006-10-25 15:28:50 · answer #6 · answered by raymund 2 · 1⤊ 0⤋
Raymund is right. 16X23.
2006-10-25 15:33:46 · answer #7 · answered by daca_moracca 3 · 1⤊ 0⤋