You can isolate the length (l{\displaystyle l}) or the width (w{\displaystyle w}). Set this formula aside. You will plug it into the area formula later. For example, if you know the width of a rectangle is 2 cm more than the length, you can write a formula for w{\displaystyle w}: w=l+2{\displaystyle w=l+2}. The formula is A=lw{\displaystyle A=lw}, where A{\displaystyle A} equals the area of the rectangle, l{\displaystyle l} equals the length of the rectangle, and w{\displaystyle w} equals the width of the rectangle. You can use this method if you know the perimeter of the rectangle, except you would now set up the perimeter formula instead of the area formula. The formula for the perimeter of a rectangle is P=2(w+l){\displaystyle P=2(w+l)}, where w{\displaystyle w} equals the width of the rectangle, and l{\displaystyle l} equals the length of the rectangle. Make sure you substitute for the variable A{\displaystyle A}. For example, if the area of the rectangle is 35 square centimeters, your formula will look like this: 35=lw{\displaystyle 35=lw}. Since you are working with a rectangle, it doesn’t matter whether you work with the l{\displaystyle l} or w{\displaystyle w} variable. For example, if you found that w=l+2{\displaystyle w=l+2}, then you would substitute this relationship for w{\displaystyle w} in the area formula:35=lw{\displaystyle 35=lw}35=l(l+2){\displaystyle 35=l(l+2)} To do this, use the distributive property to multiply the terms in parentheses, then set the equation to 0. For example:35=l(l+2){\displaystyle 35=l(l+2)}35=l2+2l{\displaystyle 35=l^{2}+2l}0=l2+2l−35{\displaystyle 0=l^{2}+2l-35} For complete instructions on how to do this, read Solve Quadratic Equations. For example, the equation 0=l2+2l−35{\displaystyle 0=l^{2}+2l-35} can be factored as 0=(l+7)(l−5){\displaystyle 0=(l+7)(l-5)}. To do this, set each term to zero and solve for the variable. You will find two solutions, or roots, to the equation. For example:0=(l+7){\displaystyle 0=(l+7)}−7=l{\displaystyle...

How would you rephrase that briefly using Chinese?
写下能够说明两条边边长之间关系的等式。 列出矩形的面积公式。 将矩形的面积代入到公式中。 将长或宽的关系表达式代入公式中。 列出二次方程。 将二次方程因式分解。 求l{\displaystyle l}的值。 将长或宽的值代入到关系表达式中。 列出勾股定理的公式。 将宽和长代入到公式中。 算出宽和长的平方，然后相加求和。 将等式两边开平方。