Question

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class 7 worksheets -4 chapter-6 dav book​

Answer 1

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Answer 2

Answer:

$1.) \: ( {x}^{2} - 4xy + {y}^{2} )(x - 2y) \\ lets \: \: put \: \: the \: \: value \: \: of \: \: x \: \: and \: \: y \\ x = 3 \: \: and \: \: y = 2 \\ ( {3}^{2} - 4 \times 3 \times 2 + {2}^{2} )(3 - 2 \times 2) \\ (9 - 24 + 4)(3 - 4) \\ (9 - 20)( - 1) \\ ( - 11)( - 1) \\ = 11 \: \: \: \: ans \\ 2.)(7 {x}^{2} y - 3 {z}^{2} )(x + y + z) \\ put \: \: the \: \: value \: \: of \: \: x \: \:y \: \: and \: \: z \\ x = 1 \: \: y = 1 \: \: z = - 1 \\ (7(1 {)}^{2} 1 - 3( - 1 {)}^{2} )(1 + 1 + ( - 1)) \\ = (7 - 3(1))(2 - 1) \\ = (7 - 3)(1) \\ = 4 \times 1 \\ = 4 \: \: ans \:$

these are the first 2 questions

$3.)(4 {a}^{2} - 6ab + 9 {b}^{2} )(2a + 3b) \\ now \: \: put \: \: the \: \: value \: \: of \: \: a \: \: and \: \: y \\ a = 2 \: \: and \: \: b = 1 \\ (4 ({2})^{2} - 6 \times 2 \times 1 + 9(1 {)}^{2} )(2(2) + 3(1)) \\ = (4 \times 4 - 12 + 9)(4 + 3) \\ = (16 - 12 + 9)(7) \\ = (4 + 9) \times 7 \\ = 13 \times 7 \\ = 91$answer

$4.)( {m}^{2} - 10m + 25)(m - 5) \\ now \: \: put \: \: value \: \\ m = - 2 \\ (( - 2 {)}^{2} - 10( - 2) + 25)( - 2 - 5) \\ (4 + 20 + 25)( - 7) \\ (49)( - 7) \\ = - 343$answer

$5.)( {p}^{2} + {q}^{2} + {r}^{2} )(pq + qr) \\ put \: \: values \: \\ p = 2 \: \: \: \: q = - 3 \: \: \: \: r = 1 \\ (( {2})^{2} + ( - 3 {)}^{2} + (1 {)}^{2})(2 \times ( - 3) + ( - 3) \times 1) \\ (4 + 9 + 1)( - 6 + ( - 3)) \\ (14)( - 6 - 3) \\ (14)( - 9) \\ = ( - 126)$answer

$( \frac{5}{4} {x}^{2} - \frac{3}{2} xy)( x + y + {y}^{2} ) \\ put \: \: values \: \\ x = 2 \: \: \: \: \: y = 2 \\ ( \frac{5}{4} (2 {)}^{2} - \frac{3}{2} \times 2 \times 2)(2 + 2 + {2}^{2} ) \\ ( \frac{5}{4} \times 4 - 3 \times 2)(4 + 4) \\ (5 - 6)(8) \\ ( - 1)(8) \\ = - 8$answer

I hope it will help you out