hello. I need help with a maths question for the further math gcse. The question asks this;
a rectangular lawn is 21m squared and it is 2m longer than it is wide. a gardener wants to edge the garden with edging strips sold i lengths of 1 1/2 m. How many will she need to buy?
I am stuck on how to start this. Can you please help me on how to do it? The rest of the exercise has been on quadratics (quadratic formula) so i think it might need that. If you could help with the workings as well that would be great thanks!
Maths Help Quadratics?
2015-10-14 7:56 pm
回答 (2)
2015-10-16 2:33 am
Let the width be x m
Length = x+2 m
AREA = LENGTH *WIDTH
21 = (x+2) *x
x^2 +2x = 21
ADD 1
x^2 +2x+1 = 22
( x+1)^2 = 22
Rejecting the negative, x = \/22 - 1 = 3.69m
Width = 3.69m Length = 5.69 m
Perimeter = 2 ( 5.69+ 3.69) = 18.76 m
18.76 /1.5 = 12.5
ANSWER 13 strips
Length = x+2 m
AREA = LENGTH *WIDTH
21 = (x+2) *x
x^2 +2x = 21
ADD 1
x^2 +2x+1 = 22
( x+1)^2 = 22
Rejecting the negative, x = \/22 - 1 = 3.69m
Width = 3.69m Length = 5.69 m
Perimeter = 2 ( 5.69+ 3.69) = 18.76 m
18.76 /1.5 = 12.5
ANSWER 13 strips
2015-10-14 8:04 pm
"rectangle is 2m longer than it is wide"
L = W+2
area = 21 m²
LW = 21
(W+2)W = 21
W² + 2W - 21 = 0
quadratic formula
W = [-2 ± √(2² – 4·1(-21))] / [2·1]
= [-2 ± √88] / 2
= [-2 ± 2√22] / 2
= -1 ± √22
W ≅ 3.69
L = 5.69
perimeter = 2W+2L = 18.75 m
Buy 13 strips
L = W+2
area = 21 m²
LW = 21
(W+2)W = 21
W² + 2W - 21 = 0
quadratic formula
W = [-2 ± √(2² – 4·1(-21))] / [2·1]
= [-2 ± √88] / 2
= [-2 ± 2√22] / 2
= -1 ± √22
W ≅ 3.69
L = 5.69
perimeter = 2W+2L = 18.75 m
Buy 13 strips
收錄日期: 2021-04-21 14:37:55
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