Question

x2-4x-21. factorise​

Answer 1

Answer:

x=7,-3

Step-by-step explanation:

by factorisation method or splitting the middle.term

-21=-7×3

-7+3=-4

${x}^{2} - 7x + 3x - 21 \\x (x - 7) + 3(x - 7) \\ (x - 7)(x + 3) \\ x - 7 = 0 \: and \: x + 3 = 0 \\ x = 7 \: and \: x = - 3$

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