Question

Which of the following is a quadratic equation? 

1. x² + 2x+ 1 = (4 – x)² + 3

2. -2x² = (5 – x)[2x – 25]

3. (k + 1)x² + 32 x = 7, where k = -1

4. x³ – x² = (x – 1)³​

Help me with this!!

Answer 1

Answer:

1.x2+2x+1(4−x)2+3

Use binomial theorem (a−b)2=a2−2ab+b2 to expand (4−x)2.

x2+2x+1(16−8x+x2)+3

Use the distributive property to multiply 1 by 16−8x+x2.

x2+2x+16−8x+x2+3

Combine 2x and −8x to get −6x.

x2−6x+16+x2+3

Combine x2 and x2 to get 2x2.

2x2−6x+16+3

Add 16 and 3 to get 19.

2x2−6x+19