1.

Solve by identity 2 (x-7)²​

Answer»

Answer:

● \large\fbox{\sf (x - <klux>7</klux>)^2 = x^2 - 14x + 49}

Step-by-step EXPLANATION:

→ As we know, we have to use second IDENTITY which is \sf{(x - y)^2 = x^2 - 2xy + y^2}.

→ Now, below is the solution :

= (x - 7)² = (x)² - 2(x)(7) + (7)²

= (x - 7)² = x² - 14x + 49

Know more:

There are many other IDENTITIES too. They are written below :

  1. (x + y)² = x² + 2xy + y²
  2. (x - y)² = x² - 2xy + y² (used in the above SUM)
  3. x² - y² = (x + y) (x - y)
  4. (x + a) (x + b) = x² + (a + b)x + ab
  5. (x + y + z)² = x² + y² + z² + 2xy + 2yz + 2zx
  6. (x + y)³ = x³ + y³ + 3xy (x + y) or 3x²y + 3xy²
  7. (x - y)³ = x³ - y³ - 3xy (x - y) or - 3x²y + 3xy²
  8. x³ + y³ + z³ = (x + y + z) (x² + y² + z² - xy - yz - zx)

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