Solve (a-4/5y)(a+4/5y)

$$( a - \frac { 4 } { 5 } y ) ( a + \frac { 4 } { 5 } y )$$

Evaluate

$$-\frac{16y^{2}}{25}+a^{2}$$

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}.

$$a^{2}-\left(\frac{4}{5}y\right)^{2}$$

Expand \left(\frac{4}{5}y\right)^{2}.

$$a^{2}-\left(\frac{4}{5}\right)^{2}y^{2}$$

Calculate \frac{4}{5} to the power of 2 and get \frac{16}{25}.

$$a^{2}-\frac{16}{25}y^{2}$$

Expand

$$-\frac{16y^{2}}{25}+a^{2}$$

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}.

$$a^{2}-\left(\frac{4}{5}y\right)^{2}$$

Expand \left(\frac{4}{5}y\right)^{2}.

$$a^{2}-\left(\frac{4}{5}\right)^{2}y^{2}$$

Calculate \frac{4}{5} to the power of 2 and get \frac{16}{25}.

$$a^{2}-\frac{16}{25}y^{2}$$