Question

Question 8. Simplify 7x2

(3x – 9) + 3(x-1) and find its values for x = -1 and x = 6​

Answer 1

Answer:

put the value instead of x

(3*-1- 9)+3(6-1)

(-3-9)+ (18-3)

-12+15

3

hope this will help you

Answer 2

Answer:

$7x {}^{2} (3x - 9) + 3(x - 1) \\ = 21x {}^{3} - 63x {}^{2} + 3x - 3 \\for \: \: x = - 1 \\ 21x {}^{3} - 63x {}^{2} + 3x - 1 \\ = 21 \times ( - 1) {}^{3} - 63 \times ( - 1) {}^{2} + 3 \times ( - 1) - 1 \\ = 21 \times ( - 1) - 63 \times 1 + ( - 3) - 1 \\ = - 21 - 63 - 3 - 1 \\ = - (21 + 63 + 3 + 1) \\ = - 88 \\ for \: \: \: x = 6 \\ 21x {}^{3} - 63x {}^{2} + 3x - 1 \\ = 21 \times 6 {}^{3} - 63 \times 6 {}^{2} + 3 \times 6 - 1 \\ = 21 \times 216 - 63 \times 36 + 18 - 1 \\ = 4536 - 2268 + 18 - 1 \\ = 4536 + 18 - (2268 + 1) \\ = 4554 - 2269 \\ = 2285$