Question

1/2( x + 3 + x + 9)(3x - 4) = 80​

Answer 1

Answer:

Question:-

1/2(x+3+x+9)(3x-4)=80

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Required Answer:-

1/2 x (x+3+x+9)(3x-4)=80

1/2 x (2x+12)(3x-4)=80

1/2 x 2x (3x-4) + 12 (3x-4)= 80

1/2 x 6x^2+8x+36x-48=80

1/2 x 6x^2+44x-48-80=0

1/2 x 6x^2+44x-128=0

1 x 12x^2+88x-256=0 -(multiply throughout by 2)

6x^2+44x-128=0 -(divide throughtout by 2)

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Now either solve by formula method or by factorisation method

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To make it easy and to avoid calculation mistakes you can go with formula method

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so by Formula Method;

6x^2+44x-128=0

comparing with ax^2+bx+c=0 we get,

a=6, b=44, c= -128

b^2-4ac=(44)^2-4(6)(-128)

b^2-4ac=1936+3072

b^2-4ac=5008

x= -b±root b^2-4ac/2a

x= -44 ± root 5008/2(6)

x= -44 ± 12 root2/12

x= 2(-22±6root2)/12

x= -22± 6 root2/6

x= -22 + 6 root2/6 or x= -22-6 root2/6

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hope it help you.