Question

solve by identity 2 (x-7)²​

Answer 1

Answer:

● $\large\fbox{\sf (x - 7)^2 = x^2 - 14x + 49}$

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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Answer 2

Answer :

${ \huge{ \fbox{{(x-7)}^{2} = {x}^{2} - 2 \times x \times 7 + {7}^{2}}}}$

The identity used :

$(a - b) {}^{2} = {a}^{2} - 2ab + {b}^{2}$

There are many such identities in math .

Some of the are :

• $\fbox{ {(a + b)}^{2} = {a}^{2} + 2ab + {b}^{2}}$
• $\fbox{ {(a - b)}^{2} = {a}^{2} - 2ab + {b}^{2}}$
• $\fbox{(a + b)(a - b) = {a}^{2} - {b}^{2} }$
• $\fbox{(x + a)(x + b) = {x}^{2} + (a + b)x + ab}$
• $\fbox{ {(a + b)}^{3} = {a}^{3} + {b}^{3} + 3ab(a + b)} }$
• $\fbox{ {(a - b)}^{3} = {a}^{3} - {b}^{3} - 3ab(a - b)}$