Question

Find the following using suitable identities.
a. (7a – 4b) (7a + 4b)
b. 501 x 502

Answer 1

Answer:

a) (a+b) (a-b)=a²-b²

means (7a)²-(4b)²

49a²-16b²

Step-by-step explanation:

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Answer 2

Answer:

Step-by-step explanation:

First one

• (7a – 4b) (7a + 4b)

• $(7a)^{2} - (4b)^{2}$                                                 (∴ $(x + y ) ( x + y ) = x^{2} - y^{2}$ )
• 49$a^{2}$ - 16$b^{2}$  

Second one

• 501 x 502
• ( 500 + 1 ) ( 500 + 2 )
• $(500)^{2}$ + ( 1 + 2 )500 + ( 1 x 2 )             (∴(x + a)(x+b) = $x^{2}$ + (a+b)x + (a x b )
• 250000 + 1500 + 2
• 251502

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