Simplify the expression and evaluate them as directed :
(i) x(x - 3) +2 for x = 1
(ii) 3y (2y - 7) -3 (y-4)-63 for y = -2

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Solution

(i) We have, $x (x - 3) + 2 = x^{2} - 3 x + 2$
For x = 1, we have
$x^{2} - 3 x + 2 = (1)^{2} - 3 \times 1 + 2 = 1 - 3 + 2 = 3 - 3 = 0$

(ii) We have,
3y (2y - 7) - 3 (y - 4) - 63
= $6 y^{2} - 21 y$ -(3y-12)-63
= $6 y 2 - 21 y - 3 y + 12 - 63$
= $6 y^{2} - 24 y - 51$
For y = -2, we have
$6 y^{2} - 24 y - 51 = 6 \times (- 2)^{2} - 24 (- 2) - 51$
= 6 × 4 + 24 × 2 -51 = 24 + 48 - 51 = 72 - 51 = 21

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3 y (2 y - 7) - 3 (y - 4) - 63

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3 y (2 y - 7) - 3 (y - 4) - 63

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