It will need to be 9 as 27 by 8 is 216 and 23 by 9 is 207 and the you subtract 207 from 216 and get 9
If you're solving for x, you'd move all the terms containing x to the left side of the equation:
d^2y/dx^2+4y/x-12y-cos^2(x)+sin^2(x)=0
If you're solving for y, you'd simplify both sides of the equation, then isolating the variable:
y=xcos(2x)
Start by dividing all terms by 4, to reduce this expression: |x+1| < 3.
Case 1: x+1 is already positive. The abs. val. operator does not change
anything. Then x+1<3, or x<2.
Case 2: (x+1) is negative. The abs. val. operator, in effect, puts a - sign in
front of (x+1): -(x+1)<3. Distributing the - sign: -x - 1 < 3. Adding 1 to both sides: -x < 4. We want to solve for positive x, so we mult. both sides of
-x<4 by -1 AND change the direction of the inequality symbol:
x > -4
Thus, the solution set is (-4,2): All real numbers between -4 and 2.
Let one pen be

and one pencil as

, we can produce two equations in terms of

and


------> Equation 1

------> Equation 2
We can use either Elimination or Substitution method. Let's try the substitution method
Rearranging equation one to get

and substitute into equation 2, gives





We can use either equation one or equation to work out




The price of one pen is $0.85
The price of one pencil is $0.32