Commerce (English Medium) Class 12 - CBSE Question Bank Solutions

Find the points on the line \[\frac{x + 2}{3} = \frac{y + 1}{2} = \frac{z - 3}{2}\]  at a distance of 5 units from the point P (1, 3, 3).

Find the interval in which the following function are increasing or decreasing  f(x) = 5x³ − 15x² − 120x + 3 ?

Find the interval in which the following function are increasing or decreasing f(x) = x³ − 6x² − 36x + 2 ?

Show that the points whose position vectors are  \[- 2 \hat{i} + 3 \hat{j} , \hat{i} + 2 \hat{j} + 3 \hat{k}  \text{ and }  7 \text{ i}  - \text{ k} \]  are collinear.

Find the interval in which the following function are increasing or decreasing f(x) = 2x³ − 15x² + 36x + 1 ?

Find the interval in which the following function are increasing or decreasing f(x) = 2x³ + 9x² + 12x + 20  ?

Find the cartesian and vector equations of a line which passes through the point (1, 2, 3) and is parallel to the line  \[\frac{- x - 2}{1} = \frac{y + 3}{7} = \frac{2z - 6}{3} .\] 

The cartesian equation of a line are 3x + 1 = 6y − 2 = 1 − z. Find the fixed point through which it passes, its direction ratios and also its vector equation.

Find the vector equation of the line passing through the point A(1, 2, –1) and parallel to the line 5x – 25 = 14 – 7y = 35z.

Find the interval in which the following function are increasing or decreasing f(x) = 2x³ − 9x² + 12x − 5 ?

Show that the three lines with direction cosines \[\frac{12}{13}, \frac{- 3}{13}, \frac{- 4}{13}; \frac{4}{13}, \frac{12}{13}, \frac{3}{13}; \frac{3}{13}, \frac{- 4}{13}, \frac{12}{13}\] are mutually perpendicular. 

Find the interval in which the following function are increasing or decreasing f(x) = 6 + 12x + 3x² − 2x³ ?

Show that the line through the points (1, −1, 2) and (3, 4, −2) is perpendicular to the through the points (0, 3, 2) and (3, 5, 6).

Find the interval in which the following function are increasing or decreasing  f(x) = 2x³ − 24x + 107  ?

Show that the line through the points (4, 7, 8) and (2, 3, 4) is parallel to the line through the points (−1, −2, 1) and, (1, 2, 5).

Find the interval in which the following function are increasing or decreasing f(x) = −2x³ − 9x² − 12x + 1  ?

Find the cartesian equation of the line which passes through the point (−2, 4, −5) and parallel to the line given by  \[\frac{x + 3}{3} = \frac{y - 4}{5} = \frac{z + 8}{6} .\]

Find the interval in which the following function are increasing or decreasing f(x) = (x − 1) (x − 2)² ?

Show that the lines \[\frac{x - 5}{7} = \frac{y + 2}{- 5} = \frac{z}{1} \text { and }\frac{x}{1} = \frac{y}{2} = \frac{z}{3}\]  are perpendicular to each other. 

Find the interval in which the following function are increasing or decreasing f(x) = x³ − 12x² + 36x + 17 ?