Question

`[(5sqrt(7) + sqrt(7)) + (4sqrt(7) + 8sqrt(7))] - (19)^2` = ?

Options

• 143

• `72sqrt(7)`

• 134

• `70sqrt(7)`

Answer 1

143

Explanation:

`[(5sqrt(7) + sqrt(7)) xx (4sqrt(7) + 8sqrt(7))] - (19)^2` = ?

⇒ `(6sqrt(7) xx 12sqrt(7)) - (361)` = ?

⇒ `72 xx sqrt(7) xx sqrt(7) = 361` = ?

∴ ? = 504 – 361 = 143