Use the distributive property to rewrite \( 7(3-x) \). \( 7(x-3) \) \( 21-7 x \) \( 7 x-21 \) \( (3-x) 7 \)

Write an equation that expresses the following relationship. \( u \) varies directly with \( p \) and inversely with \( d \) In your equation, use \( k \) as the constant of proportionality. पा]

Write an equation that expresses the following relationship. \[ d \text { varies directly with } w \text { and inversely with the square root of } p \] In your equation, use \( k \) as the constant of proportionality.

Write an equation that expresses the following relationship. \( p \) varies jointly. with \( d \) and the square root of \( u \) In your equation, use \( k \) as the constant of proportionality. \( \square=\square \quad \frac{\square}{\square} \)

a. \( x^{2}=49 \)

b. \( x^{2}+2 x=15 \)