7(x)=26-4.9x2

Solution for 7(x)=26-4.9x2 equation:

7(x)=26-4.9x^2

We move all terms to the left:

7(x)-(26-4.9x^2)=0

We get rid of parentheses

4.9x^2+7x-26=0

a = 4.9; b = 7; c = -26;
Δ = b2-4ac
Δ = 72-4·4.9·(-26)
Δ = 558.6
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(7)-\sqrt{558.6}}{2*4.9}=\frac{-7-\sqrt{558.6}}{9.8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(7)+\sqrt{558.6}}{2*4.9}=\frac{-7+\sqrt{558.6}}{9.8}
$