Correct Answer: B. \(\frac{-y}{2y + x}\)

Explanation

\(y^2 + xy = 5\)

By implicit differentiation

\(=2y\frac{dy}{dx}+y+x\frac{dy}{dx}=0\)

\(=2y\frac{dy}{dx}+x\frac{dy}{dx}=-y\)

Factor out \(\frac{dy}{dx}\)

\(=\frac{dy}{dx}(2y+x)=-y\)

\(∴\frac{dy}{dx}=\frac{-y}{2y + x}\)

Correct Answer: A. substrates

Explanation

A reactant is a substance that undergoes change during a reaction. During an enzyme reaction specifically, the reactant is called the substrate, as a substrate is the substance in which an enzyme acts on and changes.

Correct Answer: C. Subsistence farming

Explanation

(a)Rock weathering is defined as the breaking down of rocks into tiny pieces to form soil.

(b) Four factors that affects the formation of soil are

(i) Parent material e.g granite will form sandy soil

(ii) Climate: Elements like temperature, water and wind help to break down rocks

(iii) Topography: Steep slopes increase the rat, break soil formation.

(iv) Living organisms or biotic factors: The influence or activities of plants and animals help to rock break down rocks.

(c) Four types of chemical weathering are:

(i) Solution: Water dissolves soluble

(ii) Oxidation: This is the reaction of oxygen with rocks resulting in disintegration

(iii) Carbonation: This involves the dissolution of carbon dioxide with rain water to form a weak carbonic acid. This acid can dissolve rocks

(iv) Hydration: This is the attachment of water with rock minerals which results in chemical alteration of the mineral

Correct Answer: B. T = R - \(\frac{15P^3}{Q}\)

Explanation

Cubic both sides; P³ = \(\frac{Q(R - T)}{15}\)

(cross multiplication) Q(R - T) = 15P³

(divide both sides by Q); R - T = 15\(\frac{1}{Q}\)

(subtract r from both sides) - T = \(\frac{15P^3}{Q - R}\)

T = R - \(\frac{15P^3}{Q}\)

Correct Answer: B. Glucose and oxygen

Explanation

The primary products of photosynthesis are glucose and oxygen. During photosynthesis, plants use sunlight, water, and carbon dioxide to produce glucose, a simple sugar that serves as the main source of energy for the plant. Oxygen is also produced as a byproduct of photosynthesis and is released into the atmosphere.

Correct Answer: D. marketing his crops

Correct Answer: C. ii and iii only

Correct Answer: D. 5\(\sqrt{6}\)cm

Explanation

tan 6^o = \(\frac{|PR|}{|QR|}\)

\(\sqrt{3} = \frac{|PR|}{5}\)

= |PR| = \(5 \sqrt{3}\)cm

sin 45 = \(\frac{|PR|}{|PS|}\)

\(\frac{1}{\sqrt{2}}\) = \(\frac{5 \sqrt{3}}{|PS|}\)

|PS| = \(5 \sqrt{3}\) x \(\sqrt{2}\)

= 5\(\sqrt{6}\)cm

Correct Answer: B. secchi disc