Area = width * height
since the window is 20 inches higher than the width:
width +20 = height
640 = width * width+20
640 = width^2 +20*width
width^2 +20*width - 640 = 0
width = 17.203
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Double Check
if width = 17.203 then height = 37.203
area = 17.203 * 37.203 = 640 square inches Correct!!
<span>7r²+9=1
</span><span>the equation is contradictory, just to prove
7r</span>² + 9 = 1
7r² + 9 -1 = 0
7r² + 8 = 0
<span>We write the equation in the form of products of
</span>
7 * (r² + 8/7) = 0
<span>the product is equal to 0 when one of the factors is zero
</span>
7≠0 ∨ (r² + 8/7) = 0
r² ≠ - 8/7
<span>any number squared is not negative.
</span><span>We proved that none of the factors is not equal to zero , so the right side of the equation is not equal to the left . The equation is contradictory</span>
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