若2x^2-5x=0,求代数式(15x^2-18x+9)-(-3x^2+19x-31)-8x的值

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若2x^2-5x=0,求代数式(15x^2-18x+9)-(-3x^2+19x-31)-8x的值若2x^2-5x=0,求代数式(15x^2-18x+9)-(-3x^2+19x-31)-8x的值若2x^

若2x^2-5x=0,求代数式(15x^2-18x+9)-(-3x^2+19x-31)-8x的值
若2x^2-5x=0,求代数式(15x^2-18x+9)-(-3x^2+19x-31)-8x的值

若2x^2-5x=0,求代数式(15x^2-18x+9)-(-3x^2+19x-31)-8x的值
(15x^2-18x+9)-(-3x^2+19x-31)-8x
=15x^2-18x+9+3x^2-19x+31-8x
=15x^2+3x^2-18x-19x-8x+9+31
=18x^2-45x+40
=9(2x^2-5x)+40
=9*0+40
=40

(15x^2-18x+9)-(-3x^2+19x-31)-8x
=15x²-18x+9+3x²-19x+31-8x
=18x²-45x+31
=9(2x²-5x)+31 2x^2-5x=0
=31

(15x^2-18x+9)-(-3x^2+19x-31)-8x
=15x^2-18x+9+3x^2-19x+31-8x
=18x^2-45x+40
=9(2x^2-5x)+40
=0+40
=40

15x^2-18x+9)-(-3x^2+19x-31)-8x
=15x^2-18x+9+3x^2-19x+31-8x
=15x^2+3x^2-18x-19x-8x+9+31
=18x^2-45x+40
=9(2x^2-5x)+40
=9*0+40
=40