Solve C = (9x - 5)(9x + 5) | Equatix - Math Solver

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Example

3(r+2s)=2t-4

a⋅(b-2)=3b

3(r+2s)=2t-4

a⋅(b-2)=3b

Question

$$C=(9x-5)(9x+5)$$

Solve for C

$C=81x^{2}-25$

Solution Steps

Consider $\left(9x-5\right)\left(9x+5\right)$. Multiplication can be transformed into difference of squares using the rule: $\left(a-b\right)\left(a+b\right)=a^{2}-b^{2}$. Square $5$.

$$C=\left(9x\right)^{2}-25$$

Expand $\left(9x\right)^{2}$.

$$C=9^{2}x^{2}-25$$

Calculate $9$ to the power of $2$ and get $81$.

$$C=81x^{2}-25$$

Solve for x (complex solution)

$x=-\frac{\sqrt{C+25}}{9}$
$x=\frac{\sqrt{C+25}}{9}$

Solve for x

$x=-\frac{\sqrt{C+25}}{9}$
$x=\frac{\sqrt{C+25}}{9}\text{, }C\geq -25$