Question

Simplify : (i) 3x(4x-5)+3. Find the value for (a) x=1/2. Solve (b) part. ​

Answer 1

Answer:

Step-by-step explanation:

(a)x=3

=3x3(4x3-5)+3

=9(12-5)+3

=9x7+3

=63+3

=66

(b)x=1/2

=3x1/2(4x1/2-5)+3

=3/2(2-5)+3

=3/2x(-3)+3

=(-9/2)+3

=(-9+6)/2

=(-3/2)

Answer 2

3x (4x – 5) + 3

3x (4x – 5) + 3 = (3x × 4x) – (3x × 5) + 3

3x (4x – 5) + 3 = 12x2 – 15x + 3

Substitute the value of (i) x = 3 in 12x2 – 15x + 3

12x2 – 15x + 3

Put x = 3

⇒ 12 × (32) – (15 × 3) + 3

⇒ 12 × 9 – 45 + 3

⇒ 108 – 45 + 3

⇒ 66

Substitute the value of (ii) x =1/2 in 12x2 – 15x + 3

12x2 – 15x + 3

Put = 1/2

⇒ 12 × (1/2)2 – (15 × 1/2) + 3

⇒ 12 × 1/4 – (15 × 1/2) + 3

⇒ 3 – 15/2 + 3

⇒ 6 – 15/2

⇒ (12 – 15)/2
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