Area = length *width
A = x²
3x² = (x+10)(x+12)
3x² = x²+10x+12x+120
3x² = x²+22x+120
3x²-3x² = x²+22x+120-3x²
0 = -2x²+22x+120
Factor to solve for x:
-2(x²-11x-60)
(x+4)(x-15)
x = -4 & x = 15 but we can't have a negative length so we eliminate 4. The length of the square is 15 cm.

4 0

2 years ago

7x - 2 = 2y

ser-zykov [4K]

$\left\{\begin{array}{ccc}7x-2=2y\\3x=2y-1\end{array}\right\\\\substitution:\\\\3x=7x-2-1\\3x-7x=-3\\-4x=-3\ \ \ /:(-4)\\x=\frac{3}{4}\\\\2y=7\cdot\frac{3}{4}-2=\frac{21}{4}-2=\frac{21}{4}-\frac{8}{4}=\frac{13}{4}\\2y=\frac{13}{4}\ \ \ \ /:2\\y=\frac{13}{8}\\\\Answer:x=\frac{3}{4};\ y=\frac{13}{8}.$

6 0

3 years ago