Question

How do you use algebra to solve (x−1)(x+2)=18?

Answer 1

$(x - 1)(x + 2) = 18 \\ {x}^{2} + 2x - x + 2 = 18 \\ {x}^{2} + x = 18 - 2 \\ {x }^{2} + x = 16 \\ x + x = \sqrt{16 } \\ 2x = 4 \\ x = 4 \div 2 \\ x = 2 \\ \\ may \: it \: will \: help \: you$

Answer 2

The correct answer is "x = -5" and "x = 4".

Step-by-step explanation:

$The \ given \ expression \ is:\\(x-1)(x+2)=18\\On \ multiplying \ the \ above \ binomials,we \ get\\x(x+2)-1(x+2)=18\\x^2+2x-x-2=18\\x^2+x-2=18\\On \ subtracting \ "18" \ from \ both \ sides,we \ get\\x^2+x-2-18=18-18\\x^2+x-20=0\\On \ factorizing \ the \ above \ equation,we \ get\\x^2+5x-4x-20=0\\x(x+5)-4(x+5)=0\\(x+5)(x-4)=0\\x+5=0\\x=-5\\x-4=0\\x=4$

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