Find mean proportional of

If (a + b+ c)(a –b + c) = a² + b² + c² , show that a, b, c are in continued proportion.

If and a, b, c >0, then show that,

i. (a + b+ c)(b – c) = ab – c²

ii. (a² + b²)(b² + c²) = (ab + bc)²

iii. (a² + b²)/ab = (a + c)b

Select the appropriate alternative answer for the following questions.

If 6 : 5 = y : 20 then what will be the value of y?

Select the appropriate alternative answer for the following questions.

What is the ratio of 1 mm to 1 cm?