CBSE Class 10 Maths 2018 Question Paper Solution

Section A contains 6 questions of 1 mark each. Scroll down for explanatory answer and video solution to all six 1-mark questions. Questions appeared from Quadratic Equations, Real Numbers, Coordinate Geometry, Arithmetic Progressions, Trigonometry, and Triangles.

1. If x = 3 is one root of the quadratic equation x² – 2kx – 6 = 0, then find the value of k.

   Hint to solve this Quadratic Equations question

   Because 3 is a root of the equation, substitute the value of x as 3 in the equation and solve to find the value of k.

   Explanation Video Solution Quadratic Equations

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2. What is the HCF of smallest prime number and the smallest composite number?

   Hint to solve this Real Numbers problem

   What is the smallest prime number? What is the smallest composite number?
   
   Compute the HCF of these two numbers.

   Explanation Video Solution Real Numbers

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3. Find the distance of a point P(x, y) from the origin.

   Hint to solve this Coordinate Geometry Question

   Concept: The formula to compute the distance between two points whose coordinates are (x₁, y₁) and (x₂, y₂).
   Approach: One of the points is the origin (0, 0). Let it be (x₁, y₁)
   The second point is P(x, y). Let it be (x₂, y₂).
   Substitute these values in the formula to find the distance between two points to find the answer.

   Explanation Video Solution Coordinate Geometry

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4. In an AP, if the common difference (d) = - 4, and the seventh term (a₇) is 4, then find the first term.

   Hint to solve this CBSE 2018 1 mark Arithmetic Progressions problem

   Approach: The nth term of an AP a_n = a₁ + (n - 1)d, where a₁ is the first term of the AP and 'd' is the common difference.
   Given Data: a₇ = 4 and d = (-4). So, n = 7.
   Substitute: The above values in the equation to find the nth term a_n and find a₁.

   Explanation Video Solution Arithmetic Progressions

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5. What is the value of (cos² 67° - sin² 23°)?

   Hint to solve this CBSE 2018 1 mark Trigonometry question

   Concept: Trigonometric values of complementary angles.
   Step 1: Rewrite cos 67 as cos (90 - 23).
   Step 2: Apply properties of trigonometric values of complementary angles and compute the answer.

   Explanation Video Solution Trigonometry

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6. Given ∆ ABC is similar to ∆ PQR. If \\frac{AB}{PQ} = \frac{1}{3}), then find \\frac{ar ∆ ABC}{ar ∆ PQR})

   Hint to solve this CBSE 2018 maths 1 mark Triangles problem

   Concept / Theorem: Ratio of the areas of two similar triangles is the square of the ratio of their corresponding sides.
   Given Data: Ratio of corresponding sides of the two similar triangles is given.
   Apply Theorem: Apply the theorem about the relation between the ratio of corresponding sides of two similar triangles and their areas to compute the answer.

   Explanation Video Solution Triangles