Question

Factorise:
${x}^{2} + 3 {x}^{2} - 28$
​

Answer 1

x^2 +3x -28 = 0

-b +√b^2-4ac/2a or -b - √b^2-4ac/2a

-3 +√9 + 112/2 or -3 - √ 9+112/2

-3 +11/2 or -3 -11 /2

8/2 or -14/2

4 or -7

Hope it helps uh!

Answer 2

$4 { x}^{2} - 28$

$= 4( { x}^{2} - 7)$

$= 4(x - \sqrt{7} )(x + \sqrt{7)}$

using identity

${a}^{2} - {b}^{2} = (a + b)(a - b)$