winter holiday homework 4

Algebra Level 2

Find the roots of (x-1)(x+2)=70

7;3 8;-9 -8;9 -9;-4

Sophie Huang by Sophie Huang , 20, China

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2 solutions

Nikhil Raj
May 31, 2017

Given , ( x − 1 ) ( x + 2 ) = 70 ⇒ x 2 + x − 2 = 70 ⇒ x 2 + x − 72 = 0 ⇒ ( x − 8 ) ( x + 9 ) = 0 ∴ x = 8 , − 9 (x - 1)(x + 2) = 70 \\ \Rightarrow x^2 + x - 2 = 70 \\ \Rightarrow x^2 + x - 72 = 0 \\ \Rightarrow (x - 8)(x + 9) = 0 \\ \therefore x = \boxed{8,-9}

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Sudoku Subbu
Feb 15, 2015

( X − 1 ) ( X + 2 ) = 70 (X-1)(X+2)=70 = > X 2 + X − 2 = 70 =>X^2+X-2=70 = > X 2 + X − 72 = 0 =>X^2+X-72=0 => ( X − 8 ) ( X + 9 ) = 0 (X-8)(X+9)=0 = > X − 8 = 0 ( o r ) X + 9 = 0 =>X-8=0(or)X+9=0 = > X = 8 ( o r ) X = − 9 =>X=8(or)X=-9 therefore the solution is 8 , − 9 8,-9

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