Q. 2x2+26x+84If 2(x+a)(x+b) is equivalent to the given expression, what is the value of ab ?
Expand expression: Expand the expression 2(x+a)(x+b) to find its equivalent quadratic form.Using the distributive property (FOIL method) to expand:2(x+a)(x+b)=2(x×x+x×b+a×x+a×b)( = 2(x^2 + (b+a)x + ab)\)
Compare expanded form: Compare the expanded form with the given quadratic expression.We have 2x2+26x+84 and 2(x2+(b+a)x+ab).By comparing coefficients, we get:For x2 term: 2=2 (coefficients match, no need for further calculation)For x term: 26=2(b+a)For constant term: 84=2ab
Solve for b+a: Solve for b+a from the x term.26=2(b+a)Divide both sides by 2 to isolate (b+a):(b+a)=226(b+a)=13
Solve for : Solve for from the constant term.\newlineDivide both sides by 222 to isolate ab:\newlineab = \frac{848484}{222}\newlineab = 424242
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