Explain how to determine whether a rectangle
is a square?

The sum of the product of 4 and x and the product of 7 and y is 61. the sum of the product of 12 and x and the product of 21 and y is 61. what are the values of x and y?

The ksp expression for the system pbcl2(s) pb+2(aq) + 2 cl-(aq) is: [pbc12][pb+2][2cl-] [pb+2][cl-]2 [pb+2][2cl-]2 [pbcl2][pb+2][cl-]2 [pb+2][2cl-]2[pbcl2]

Does anyone know how to solve and graph this: 4 + | a + 2 | < 7the only part i don't get is the "4 +"