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What is (4x+3)(x-7)=90

User Goroth
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(4x+3)(x-7)=90\\ Distribute\\ 4x^(2)-28x+3x-21=90\\ 4x^(2)-25x-21=90\\ 4x^(2)-25x-101=0\\ \\ 101\ is\ a\ prime\ number,\ so\ use\ the\ quadratic\ equation.\\ x= \frac{-b+-\sqrt{b^(2)-4ac}}{2a} \\ \frac{-(-25)+-\sqrt{(-25)^(2)-4*4*(-101)}}{2*4} \\ (25+-√(625+1616))/(8) \\ x= (25+-√(2241))/(8) \\ So\ x= (25+√(2241))/(8)\ and x= (25-√(2241))/(8) \\ These\ come\ out\ to\ be\ x=9.0424... \ and\ x=-2.7924...
User Rakholiya Jenish
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8.0k points
4 votes
it would be 16 i say
User MivaScott
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