Solve, using the quadratic formula, the equation x^2 +2x=35

suppose you have a general quadratic equation in the form ax2 + bx + c = 0, then the solutions to this quadratic equation can be found by the equation x = (-b +/- (b2-4ac)1/2)/2aThe 'plus or minus symbol' is because a quadratic equation can give you up to two real solutions. One of which can be found by putting a plus here and the other by putting a minus here. Therefore we get two equations which you can then solve to find the two values of x:x= (-b + (b2- 4ac)1/2)/2a and x= (-b - (b2- 4ac)1/2)/2aFor the equation x2+2x=35, we need to first write this in the form ax2 + bx + c = 0. We can do this by subtracting 35 from both sides, giving: x2+2x-35 = 0, then, finding our values of a, b and c, we get a=1, b=2 and c=-35.Substituting these values into our two equations for x, we get:x= (-(2) + ((2)2- 4(1)(-35))1/2)/2(1) and x= (-(2) - ((2)2- 4(1)(-35))1/2)/2(1)simplifying these equations gives:x= (-2 + (4- (140))1/2)/2 and x= (-2 - (4- (140))1/2)/2further simplification gives:x= (-2 + 12)/2 and x= (-2 + 12)/2therefore we get the answers x=5 and x=-7

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Answered by Antonia S. Maths tutor

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