Solve 4-left(7y-5right)^2

$$4- { \left(7y-5 \right) }^{ 2 }$$

Evaluate

$$-49y^{2}+70y-21$$

Solution Steps

Use binomial theorem \left(a-b\right)^{2}=a^{2}-2ab+b^{2} to expand \left(7y-5\right)^{2}.

$$4-\left(49y^{2}-70y+25\right)$$

To find the opposite of 49y^{2}-70y+25, find the opposite of each term.

$$4-49y^{2}+70y-25$$

Subtract 25 from 4 to get -21.

$$-21-49y^{2}+70y$$

Expand

$$-49y^{2}+70y-21$$

Solution Steps

Use binomial theorem \left(a-b\right)^{2}=a^{2}-2ab+b^{2} to expand \left(7y-5\right)^{2}.

$$4-\left(49y^{2}-70y+25\right)$$

To find the opposite of 49y^{2}-70y+25, find the opposite of each term.

$$4-49y^{2}+70y-25$$

Subtract 25 from 4 to get -21.

$$-21-49y^{2}+70y$$