How to solve (7x+9y)(7x-9y)

1. Factor the equation (x + 2)(x + 3) = 0. 2. Set each factor equal to zero: x + 2 = 0 and x + 3 = 0. 3. Solve for x: x = -2 and x = -3.

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Question

$$(7x+9y)(7x-9y)$$

Evaluate

$49x^{2}-81y^{2}$

Solution Steps

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

$$\left(7x\right)^{2}-\left(9y\right)^{2}$$

Expand $\left(7x\right)^{2}$.

$$7^{2}x^{2}-\left(9y\right)^{2}$$

Calculate $7$ to the power of $2$ and get $49$.

$$49x^{2}-\left(9y\right)^{2}$$

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

$$49x^{2}-9^{2}y^{2}$$

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

$$49x^{2}-81y^{2}$$

Show Solution

Expand

$49x^{2}-81y^{2}$

Solution Steps

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

$$\left(7x\right)^{2}-\left(9y\right)^{2}$$

Expand $\left(7x\right)^{2}$.

$$7^{2}x^{2}-\left(9y\right)^{2}$$

Calculate $7$ to the power of $2$ and get $49$.

$$49x^{2}-\left(9y\right)^{2}$$

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

$$49x^{2}-9^{2}y^{2}$$

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

$$49x^{2}-81y^{2}$$

Show Solution

Basic Math

Pre-Algebra

Algebra

Trigonometry

Calculus

Precalculus

Statistics

Finite Math

Linear Algebra

Chemistry

Example

Question

Evaluate

Solution Steps

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Solution Steps