Higher Plus

The point (20, 21) lies on the circle x² + y² = 841. Work out the gradient of the tangent to the circle at that point.The point (20, 21) lies on the circle x^2 + y^2 = 841. Work out the gradient of the tangent to the circle at that point.

A bag holds 3 red, 4 blue and 5 green counters. Two are taken without replacement. Given neither is green, what is the probability both are red?

On a histogram, a 10-wide bar and a 20-wide bar have the same frequency density of 2. How many more values are in the wider class?

A block has mass 390 g (to the nearest 10 g) and volume 24 cm³ (to the nearest cm³). Work out the upper bound of its density, to 2 decimal places.A block has mass 390 g (to the nearest 10 g) and volume 24 cm^3 (to the nearest cm^3). Work out the upper bound of its density, to 2 decimal places.

Simplify (x² - 7x + 6)/(x - 1).Simplify (x^2 - 7x + 6)/(x - 1).