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QUADRATIC EQUATIONS HELP HELP
by Ckf2001 Junior Cert Mathematics — 27/10/16 4

Arthur wants to fence three sides of his rectangular garden. The fourth side of the garden faces into the back of his house. He has 80 metres of fencing. Let x represent the width of his garden and let y represent the length of his garden. i) show that y = 80-2x ii) write an expression for the area of the garden in terms of x iii) if the garden has an area of 487.5m^2 find two possible values for the width and length of the garden How would I answer these I'm so stuck


4 Comments
roro123 — 27/10/16
y is 80-2x as the 3 sides add up to 80. To get the length (y) you take away the width (x) times 2 as this are has 1 length and 2 widths.
roro123 — 27/10/16
(ii) area = x times y (width times length). width=x and length= 80-2x. therefor area is (x)(80-2x) which is 80x-2x^2.
roro123 — 27/10/16
(iii) 80x-2x^2=487.5 = -2x^2+80x-487.5=0. Solve this using the -b formula.
roro123 — 27/10/16
I think they are all right, sorry if they are wrong. I didn't write out how to finish (iii) as i can't type it!!
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