Question

$using \: (x + a)(x + b) = {x \: }^{2} + (a + b)x + ab \: find$
1. 103 X 104
2. 5.1 X 5.2
3. 103 X 98
4. 9.7 X 9.8​

Answer 1

Answer:

$(1) \: \: 103 \times 104 = (100 + 3) \times (100 + 4) \\ \\ = {(100)}^{2} + 7 \times 100 + 12 \\ \\ = 10000 + 712 = 10712 \\ \\ (2) \: \: 5.1 \times 5.2 = (5 + 0.1)(5 + 0.2) \\ \\ = {(5)}^{2} + 0.3 \times 5 + 0.02 \\ \\ = 25 + 1.5 + 0.02 \\ \\ = 26.52 \\ \\ (3) \: \: 103 \times 98 = (100 + 3)(100 - 2) \\ \\ = {(100)}^{2} + 1 \times 100 - 6 \\ \\ = 10000 + 94 = 10094 \\ \\ (4) \: \: 9.7 \times 9.8 = (10 - 0.3) \times (10 - 0.2) \\ \\ = {(10)}^{2} - 0.5 \times 10 + 0.15 \\ \\ = 100 - 5 + 0.15 \\ \\= 95.15$

Answer 2

$\huge\bf{Answer:-}$

Refer the attachment.

Step-by-step explanation:

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