7.5minutes/1miles
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A = l x w
so you know that the length is 3m longer than the width, so you could use a formula to represent that
w = l + 3
you then substitute the second equation into the first to solve for l
70 = l x (l +3)
70 = l^2 + 3l
you could then rearrange the formula and solve for l using the quadratic formula
0 = l^2 + 3l - 70
l = -3 +- (square root (3)^2 - 4(1)(70)) / 2(1)
l = -3 +- (square root 9 + 280) / 2
l = -3 +- (square root 289) / 2
l = -3 +- 17 / 2
then you solve for the two seperate roots
l = -3 + 17 /2
l = 14 / 2
l = 7
or
l = -3 - 17 / 2
l = -20 / 2
l = -10
since a length cannot be negative, this root is not viable. therefore l = 7
to solve for w you would use
w = l + 3
w = 7 + 3
w = 10
hope this helps! if you did not understand a step or concept please let me know!
