Multiply and simplify. $( 10 - 9 \sqrt { 9 t } ) ( 10 + 9 \sqrt { 9 t } )$
A) $2000 - 162 t$
B) $300 - 243 t$
C) $1000 + 91 t$
D) $200 + 81 t$
E) $100 - 729 t$

Question

Quizplus · Accepted Answer

This problem uses the difference of squares formula, $a^2 - b^2 = (a - b)(a + b)$. Here, $a = 10$ and $b = 9\sqrt{9t}$. Squaring $b$ gives $81 \cdot 9t = 729t$. Thus, the simplified form is $10^2 - (9\sqrt{9t})^2 = 100 - 729t$.

Multiply and Simplify (10−99t)(10+99t)( 10 - 9 \sqrt { 9 t } ) ( 10 + 9 \sqrt { 9 t } )(10−99t​)(10+99t​)

Multiply and Simplify $( 10 - 9 \sqrt { 9 t } ) ( 10 + 9 \sqrt { 9 t } )$