Equations Solving
1. Solve the equation $n - (3 + 2n) = -6$.
Start by distributing and combining like terms:
$$n - 3 - 2n = -6$$
$$-n - 3 = -6$$
Add 3 to both sides:
$$-n = -6 + 3$$
$$-n = -3$$
Multiply both sides by $-1$:
$$n = 3$$
2. Weekend bonus: Solve
$$\frac{2^{t - y} \cdot 2^{y - 1}}{2^{y + 2}} = 8^{2y}$$
Simplify the left side by adding exponents with the same base 2:
$$\frac{2^{(t - y) + (y - 1)}}{2^{y + 2}} = 8^{2y}$$
$$\frac{2^{t - 1}}{2^{y + 2}} = 8^{2y}$$
$$2^{t - 1 - (y + 2)} = 8^{2y}$$
$$2^{t - 1 - y - 2} = 8^{2y}$$
$$2^{t - y - 3} = 8^{2y}$$
Rewrite $8$ as $2^3$:
$$2^{t - y - 3} = (2^3)^{2y} = 2^{6y}$$
Since bases are equal, exponents are equal:
$$t - y - 3 = 6y$$
$$t - 3 = 7y$$
Solve for $y$:
$$y = \frac{t - 3}{7}$$
3. Solve for $x$:
$$25^{2x} + 3(5^{2x}) = 4$$
Rewrite $25$ as $5^2$:
$$ (5^2)^{2x} + 3(5^{2x}) = 4$$
$$5^{4x} + 3 imes 5^{2x} = 4$$
Set substitution $a = 5^{2x}$, then $a^2 = 5^{4x}$:
$$a^2 + 3a - 4 = 0$$
Factor quadratic:
$$(a + 4)(a - 1) = 0$$
So $a = -4$ (not valid since $5^{2x} > 0$) or $a = 1$.
Solve $5^{2x} = 1$:
$$5^{2x} = 5^0$$
Therefore:
$$2x = 0$$
$$x = 0$$
4. Solve inequality:
$$90^x - 4(3^{2x + 1}) + 27 \geq 0$$
Rewrite $90 = 9 \times 10$ and realize $9 = 3^2$:
Though not easily factorable, express parts in base 3:
$$90^x = (9 \times 10)^x = 9^x \cdot 10^x = (3^2)^x \cdot 10^x = 3^{2x} \cdot 10^x$$
This mixes bases, so instead test critical points or rewrite inequality carefully.
Alternatively, denote $a = 3^x$. Then:
$$90^x = (9 \times 10)^x = 9^x \cdot 10^x = (3^2)^x \cdot 10^x = a^2 \cdot 10^x$$
Equation get complicated; better to handle numerical or graphing approach here.
Since a direct algebraic solution is complex, numerical or graphical methods are recommended.
**Final answers:**
- For $n$: $n = 3$
- For bonus $y$: $y = \frac{t - 3}{7}$
- For $x$ in the third problem: $x = 0$ is the solution
- For the inequality, numerical or graphing solution is needed.