What is wrong with the following equation: 4 + (10 / 5) = 6 - 2

Equations should not involve expressions on both sides.

The equation mixes different operations like +, /, and -.

The left side's expression is longer than the right side.

The two sides do not evaluate to the same value.

45% of the trees in a park are apple trees. there are 27 apple trees in the park. how many trees are in the park in all?

Celeste wants to have her hair cut and permed and also go to lunch. she knows she will need $50. the perm cost twice as much as her haircut and she needs $5 for lunch. how much does the perm cost?

Prove (a) cosh2(x) − sinh2(x) = 1 and (b) 1 − tanh 2(x) = sech 2(x). solution (a) cosh2(x) − sinh2(x) = ex + e−x 2 2 − 2 = e2x + 2 + e−2x 4 − = 4 = . (b) we start with the identity proved in part (a): cosh2(x) − sinh2(x) = 1. if we divide both sides by cosh2(x), we get 1 − sinh2(x) cosh2(x) = 1 or 1 − tanh 2(x) = .