Question

plz factorise it and i will surely mark u as brainliest ​

Answer 1

Answer:

6. (9x + y +X)(9x + y - X)

7.(25a + b + 16a - 16b)(25a + b - 16a + 16b)

8.x^3 - 25x

Step-by-step explanation:

Qno. 6 and 7 use (a^2-b^2) formula

The last one can't be factorised.

Answer 2

Answer:

$</p><p>6.\: i)9(x+y)^2 -x^2\\ \\ \\</p><p>identity- a^2-b^2 = (a+b)(a-b) \\ \\ \\</p><p>9 = 3^2 \\ \\ \\</p><p>9(x+y)^2 = [3(x+y)]^2 \\ \\ \\</p><p>= (3x+3y)^2 \\ \\ \\</p><p>by\: using\: identity\\ \\ \\</p><p>9(x+y)^2 -x^2= \\ \\ \\</p><p>(3x+3y)^2-x^2 \\ \\ \\</p><p>[(3x+3y)+x][(3x+3y)-x] \\ \\ \\</p><p>= (3x+3y+x) (3x+3y-x) \\ \\ \\</p><p>= (4x+3y)(2x+3y) \\ \\ \\</p><p>7.\: i)25(a+b)^2-16(a-b)^2 \\ \\ \\</p><p>identity- a^2-b^2 = (a+b)(a-b) \\ \\ \\</p><p>25= 5^2 \: and \: 16= 4^2\\ \\ \\</p><p>25(a+b)^2 = [5(a+b)]^2\\ \\ \\</p><p>= (5a+5b)^2 \\ \\ \\</p><p>16(a-b)^2 = [4(a-b)]^2\\ \\ \\</p><p>= (4a-4b)^2\\ \\ \\</p><p>25(a+b)^2-16(a-b)^2= \\ \\ \\</p><p>(5a+5b)^2 - (4a-4b)^2\\ \\ \\</p><p>= [(5a+5b)+(4a-4b)]\:[(5a+5b)-(4a-4b)] \\ \\ \\</p><p>= (5a+5b+4a-4b)(5a+5b-4a+4b) \\ \\ \\</p><p>= (9a+b)(a+9b) \\ \\ \\</p><p>8.\:i) x^3-25x\\ \\ \\</p><p>= x(x^2-25)\\ \\ \\</p><p>identity- a^2-b^2 = (a+b)(a-b) \\ \\ \\</p><p>= x[(x)^2 -(5)^2]\\ \\ \\</p><p>= x(x-5)(x+5)$