Let
x-------------> amount added <span>to each side
</span>A-------------> area increased----------> 84 ft²
we know that
A=(10+x)*(5+x)=84-----------> 10*5+10*x+5*x+x²
50+15x+x²=84----------> x²+15x-34=0
<span>solving the second order equation
</span>x1=-17
x2=2
the answer is x=2 ft
Answer: x-7
Step-by-step explanation:

Y = - 2x + 4
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Set the shorter side of rectangle as X m
The longer side = (4X-6) m
58 = (X + 4X -6)2
58=10X -12
70 = 10X
X = 7
The shorter side is 7 m
And the longer side is 4 x 7 -6 = 22 m