Question

(4a - 9)^2 – (4a + 9)^2
plzz help me
answer is -144a ​

Answer 1

Step-by-step explanation:

$(4a - 9) {}^{2} - (4a + 9) {}^{2} \\ = 4a {}^{2} - 2 \times 4a \times 9 + {9}^{2} - 4a {}^{2} + 2 \times 4a \times 9 + {9}^{2} \\ = 4a {}^{2} - 72a + 81 - 4a {}^{2} + 72a + 81 \\ = 4a {}^{2} - 4a {}^{2} - 72a + 72a + 81 + 81 \\ = 0 + 0 + 162 \\ = 162$

According to question

-144a =162

$\implies{a={\frac{162}{-144}}}$

$\implies{{\underline{\boxed{\sf{a=-{\frac{9}{8}}}}}}}$