A rectangle has length (x+4) cm and width (x-3) cm. Its area is 30 square centimeters. Write a quadratic equation and solve it t o find the length of the rectangle.
1 answer:
(x+4)(x-3)=30
x^2 +x -12 =30
x^2 +x =42
x^2 +x -42 =0
(i solved it by factorising: _x^2 × -42)
x^2 -6x +7x -42 =0
x(x-6) +7(x-6) 0
(x-6)(x+7)=0
x=6; x=-7
since it's a length, x can't be a negative number, so it must be 6
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