$$ if \ {1\over x}+x=4,$$ then find $${1\over x^2}+x^2$$

Direction: What approximate value will come in place of the question mark (?) in the following question? (You are not expected to calculate the exact value)

? × 350.01 ÷ 3.992² = 983 ÷ 14.001

$$ {4\over 7}×{2{4\over 5}} ÷{2\over 5}=?$$

If m + n = 1, then what will be the value of m³ + n³ + 3mn?

If 5x + 5 > 2 + 2x and 5x + 3 ≤ 4x + 5; then x can take which of the following values?

$$\left({?-0.5\over 0.2} \right)={120\over 2}$$

(0.85 % of 405 ) + (2.25 % of 550 )=?

? – 2³ =(7² – 12 ) + ( 10² -17)